infra: enable strictNullChecks in tsconfig (#2435)

13 files changed, 191 insertions, 98 deletions

diff --git a/src/definitions/date.ts b/src/definitions/date.ts
index 16cfb28a..2265a025 100644
--- a/src/definitions/date.ts
+++ b/src/definitions/date.ts
@@ -26,8 +26,9 @@ export interface DateEntryDefinition {
 
   /**
    * The short name/abbreviation of the entry.
+   * If null, the locale does not support a short name/abbreviation for the entry.
    */
-  abbr: string[];
+  abbr: string[] | null;
 
   /**
    * The wide name of the entry when used in context. If absent wide will be used instead.
diff --git a/src/definitions/definitions.ts b/src/definitions/definitions.ts
index ca495e34..c2a3b560 100644
--- a/src/definitions/definitions.ts
+++ b/src/definitions/definitions.ts
@@ -50,4 +50,4 @@ export type LocaleDefinition = {
   system?: SystemDefinition;
   vehicle?: VehicleDefinition;
   word?: WordDefinition;
-} & Record<string, Record<string, unknown> | undefined>;
+} & Record<string, Record<string, unknown>>;
diff --git a/src/locale-proxy.ts b/src/locale-proxy.ts
index 67b29d47..e99ba655 100644
--- a/src/locale-proxy.ts
+++ b/src/locale-proxy.ts
@@ -55,6 +55,30 @@ export function createLocaleProxy(locale: LocaleDefinition): LocaleProxy {
 }
 
 /**
+ * Checks that the value is not null or undefined and throws an error if it is.
+ *
+ * @param value The value to check.
+ * @param path The path to the locale data.
+ */
+export function assertLocaleData<T>(
+  value: T,
+  ...path: string[]
+): asserts value is NonNullable<T> {
+  if (value === null) {
+    throw new FakerError(
+      `The locale data for '${path.join('.')}' aren't applicable to this locale.
+  If you think this is a bug, please report it at: https://github.com/faker-js/faker`
+    );
+  } else if (value === undefined) {
+    throw new FakerError(
+      `The locale data for '${path.join('.')}' are missing in this locale.
+  Please contribute the missing data to the project or use a locale/Faker instance that has these data.
+  For more information see https://fakerjs.dev/guide/localization.html`
+    );
+  }
+}
+
+/**
  * Creates a proxy for a category that throws an error when accessing an undefined property.
  *
  * @param categoryName The name of the category.
@@ -79,20 +103,10 @@ function createCategoryProxy<
       const value = target[entryName];
       if (typeof entryName === 'symbol' || entryName === 'nodeType') {
         return value;
-      } else if (value === null) {
-        throw new FakerError(
-          `The locale data for '${categoryName}.${entryName.toString()}' aren't applicable to this locale.
-  If you think this is a bug, please report it at: https://github.com/faker-js/faker`
-        );
-      } else if (value === undefined) {
-        throw new FakerError(
-          `The locale data for '${categoryName}.${entryName.toString()}' are missing in this locale.
-  Please contribute the missing data to the project or use a locale/Faker instance that has these data.
-  For more information see https://fakerjs.dev/guide/localization.html`
-        );
-      } else {
-        return value;
       }
+
+      assertLocaleData(value, categoryName, entryName.toString());
+      return value;
     },
 
     set: throwReadOnlyError,
diff --git a/src/modules/airline/index.ts b/src/modules/airline/index.ts
index 4c1ec318..e8ac47c5 100644
--- a/src/modules/airline/index.ts
+++ b/src/modules/airline/index.ts
@@ -155,7 +155,7 @@ export class AirlineModule extends ModuleBase {
   ): string {
     const { allowNumerics = false, allowVisuallySimilarCharacters = false } =
       options;
-    const excludedChars = [];
+    const excludedChars: string[] = [];
     if (!allowNumerics) {
       excludedChars.push(...numerics);
     }
diff --git a/src/modules/color/index.ts b/src/modules/color/index.ts
index 5962ef71..57b906a3 100644
--- a/src/modules/color/index.ts
+++ b/src/modules/color/index.ts
@@ -47,17 +47,19 @@ export type Casing = 'lower' | 'upper' | 'mixed';
  *
  * @param hexColor Hex color string to be formatted.
  * @param options Options object.
- * @param options.prefix Prefix of the generated hex color. Defaults to `'0x'`.
- * @param options.casing Letter type case of the generated hex color. Defaults to `'mixed'`.
+ * @param options.prefix Prefix of the generated hex color.
+ * @param options.casing Letter type case of the generated hex color.
  */
 function formatHexColor(
   hexColor: string,
-  options?: {
-    prefix?: string;
-    casing?: Casing;
+  options: {
+    prefix: string;
+    casing: Casing;
   }
 ): string {
-  switch (options?.casing) {
+  const { prefix, casing } = options;
+
+  switch (casing) {
     case 'upper':
       hexColor = hexColor.toUpperCase();
       break;
@@ -68,8 +70,8 @@ function formatHexColor(
     // Do nothing
   }
 
-  if (options?.prefix) {
-    hexColor = options.prefix + hexColor;
+  if (prefix) {
+    hexColor = prefix + hexColor;
   }
 
   return hexColor;
@@ -360,19 +362,20 @@ export class ColorModule extends ModuleBase {
      */
     includeAlpha?: boolean;
   }): string | number[];
-  rgb(options?: {
-    prefix?: string;
-    casing?: Casing;
-    format?: 'hex' | ColorFormat;
-    includeAlpha?: boolean;
-  }): string | number[] {
+  rgb(
+    options: {
+      prefix?: string;
+      casing?: Casing;
+      format?: 'hex' | ColorFormat;
+      includeAlpha?: boolean;
+    } = {}
+  ): string | number[] {
     const {
       format = 'hex',
       includeAlpha = false,
       prefix = '#',
       casing = 'lower',
-    } = options || {};
-    options = { format, includeAlpha, prefix, casing };
+    } = options;
     let color: string | number[];
     let cssFunction: CssFunctionType = 'rgb';
     if (format === 'hex') {
@@ -380,7 +383,7 @@ export class ColorModule extends ModuleBase {
         length: includeAlpha ? 8 : 6,
         prefix: '',
       });
-      color = formatHexColor(color, options);
+      color = formatHexColor(color, { prefix, casing });
       return color;
     }
 
diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index 1be3fcb2..425bc848 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -1,3 +1,4 @@
+import { FakerError } from '../../errors/faker-error';
 import { deprecated } from '../../internal/deprecated';
 import { ModuleBase } from '../../internal/module-base';
 
@@ -401,7 +402,14 @@ export class CommerceModule extends ModuleBase {
 
     const registrantLength = groupRules.find(
       ([rangeMaximum]) => elementValue <= rangeMaximum
-    )[1];
+    )?.[1];
+
+    if (!registrantLength) {
+      // This can only happen if the ISBN_LENGTH_RULES are corrupted
+      throw new FakerError(
+        `Unable to find a registrant length for the group ${group}`
+      );
+    }
 
     const registrant = element.slice(0, registrantLength);
     const publication = element.slice(registrantLength);
diff --git a/src/modules/date/index.ts b/src/modules/date/index.ts
index a40b4772..39c85735 100644
--- a/src/modules/date/index.ts
+++ b/src/modules/date/index.ts
@@ -3,6 +3,7 @@ import type { DateEntryDefinition } from '../../definitions';
 import { FakerError } from '../../errors/faker-error';
 import { deprecated } from '../../internal/deprecated';
 import { SimpleModuleBase } from '../../internal/module-base';
+import { assertLocaleData } from '../../locale-proxy';
 
 /**
  * Converts date passed as a string, number or Date to a Date object.
@@ -15,6 +16,10 @@ function toDate(
   date: string | Date | number | undefined,
   fallback: () => Date
 ): Date {
+  if (date == null) {
+    return fallback();
+  }
+
   date = new Date(date);
   if (Number.isNaN(date.valueOf())) {
     date = fallback();
@@ -383,14 +388,15 @@ export class SimpleDateModule extends SimpleModuleBase {
         },
     legacyTo?: string | Date | number
   ): Date {
-    if (typeof options !== 'object' || options instanceof Date) {
+    if (options instanceof Date || typeof options !== 'object') {
       deprecated({
         deprecated: 'faker.date.between(from, to)',
         proposed: 'faker.date.between({ from, to })',
         since: '8.0',
         until: '9.0',
       });
-      options = { from: options, to: legacyTo };
+      // We use options as fallback for legacyTo avoid TS errors for unintended usage.
+      options = { from: options, to: legacyTo ?? options };
     }
 
     const { from, to } = options;
@@ -559,14 +565,15 @@ export class SimpleDateModule extends SimpleModuleBase {
     legacyTo?: string | Date | number,
     legacyCount: number = 3
   ): Date[] {
-    if (typeof options !== 'object' || options instanceof Date) {
+    if (options instanceof Date || typeof options !== 'object') {
       deprecated({
         deprecated: 'faker.date.betweens(from, to, count)',
         proposed: 'faker.date.betweens({ from, to, count })',
         since: '8.0',
         until: '9.0',
       });
-      options = { from: options, to: legacyTo, count: legacyCount };
+      // We use options as fallback for legacyTo avoid TS errors for unintended usage.
+      options = { from: options, to: legacyTo ?? options, count: legacyCount };
     }
 
     const { from, to, count = 3 } = options;
@@ -864,12 +871,6 @@ export class SimpleDateModule extends SimpleModuleBase {
       refDate?: string | Date | number;
     } = {}
   ): Date {
-    if (options.max < options.min) {
-      throw new FakerError(
-        `Max ${options.max} should be larger than or equal to min ${options.min}.`
-      );
-    }
-
     const mode = options.mode === 'age' ? 'age' : 'year';
     const refDate = toDate(options.refDate, this.faker.defaultRefDate);
     const refYear = refDate.getUTCFullYear();
@@ -894,6 +895,12 @@ export class SimpleDateModule extends SimpleModuleBase {
       );
     }
 
+    if (max < min) {
+      throw new FakerError(
+        `Max ${options.max} should be larger than or equal to min ${options.min}.`
+      );
+    }
+
     return new Date(this.faker.number.int({ min, max }));
   }
 }
@@ -1074,12 +1081,8 @@ export class DateModule extends SimpleDateModule {
       context?: boolean;
     } = {}
   ): string {
-    const {
-      // eslint-disable-next-line deprecation/deprecation
-      abbr,
-      abbreviated = abbr ?? false,
-      context = false,
-    } = options;
+    // eslint-disable-next-line deprecation/deprecation
+    const { abbr, abbreviated = abbr ?? false, context = false } = options;
 
     if (abbr != null) {
       deprecated({
@@ -1100,7 +1103,9 @@ export class DateModule extends SimpleDateModule {
       type = useContext ? 'wide_context' : 'wide';
     }
 
-    return this.faker.helpers.arrayElement(source[type]);
+    const values = source[type];
+    assertLocaleData(values, 'date.month', type);
+    return this.faker.helpers.arrayElement(values);
   }
 
   /**
@@ -1260,12 +1265,8 @@ export class DateModule extends SimpleDateModule {
       context?: boolean;
     } = {}
   ): string {
-    const {
-      // eslint-disable-next-line deprecation/deprecation
-      abbr,
-      abbreviated = abbr ?? false,
-      context = false,
-    } = options;
+    // eslint-disable-next-line deprecation/deprecation
+    const { abbr, abbreviated = abbr ?? false, context = false } = options;
 
     if (abbr != null) {
       deprecated({
@@ -1286,6 +1287,8 @@ export class DateModule extends SimpleDateModule {
       type = useContext ? 'wide_context' : 'wide';
     }
 
-    return this.faker.helpers.arrayElement(source[type]);
+    const values = source[type];
+    assertLocaleData(values, 'date.weekday', type);
+    return this.faker.helpers.arrayElement(values);
   }
 }
diff --git a/src/modules/finance/index.ts b/src/modules/finance/index.ts
index c443b605..33db26f0 100644
--- a/src/modules/finance/index.ts
+++ b/src/modules/finance/index.ts
@@ -24,6 +24,22 @@ export interface Currency {
 }
 
 /**
+ * Puts a space after every 4 characters.
+ *
+ * @internal
+ *
+ * @param iban The iban to pretty print.
+ */
+export function prettyPrintIban(iban: string): string {
+  let pretty = '';
+  for (let i = 0; i < iban.length; i += 4) {
+    pretty += `${iban.substring(i, i + 4)} `;
+  }
+
+  return pretty.trimEnd();
+}
+
+/**
  * Module to generate finance and money related entries.
  *
  * ### Overview
@@ -663,9 +679,9 @@ export class FinanceModule extends ModuleBase {
    */
   currencySymbol(): string {
     let symbol: string;
-    while (!symbol) {
+    do {
       symbol = this.currency().symbol;
-    }
+    } while (symbol.length === 0);
 
     return symbol;
   }
@@ -1147,7 +1163,7 @@ export class FinanceModule extends ModuleBase {
 
     const result = `${ibanFormat.country}${checksum}${s}`;
 
-    return formatted ? result.match(/.{1,4}/g).join(' ') : result;
+    return formatted ? prettyPrintIban(result) : result;
   }
 
   /**
diff --git a/src/modules/helpers/index.ts b/src/modules/helpers/index.ts
index 59eeadba..667f3a51 100644
--- a/src/modules/helpers/index.ts
+++ b/src/modules/helpers/index.ts
@@ -1120,7 +1120,7 @@ export class SimpleHelpersModule extends SimpleModuleBase {
     ) => RecordKey,
   >(
     method: TMethod,
-    args: Parameters<TMethod> = [] as Parameters<TMethod>,
+    args: Parameters<TMethod> = [] as unknown as Parameters<TMethod>,
     options: {
       /**
        * This parameter does nothing.
diff --git a/src/modules/helpers/unique.ts b/src/modules/helpers/unique.ts
index 44b3a71d..20805530 100644
--- a/src/modules/helpers/unique.ts
+++ b/src/modules/helpers/unique.ts
@@ -97,9 +97,9 @@ export function exec<
     maxRetries = 50,
     currentIterations = 0,
     compare = defaultCompare,
-    store,
+    store = {},
   } = options;
-  let { exclude } = options;
+  let { exclude = [] } = options;
   options.currentIterations = currentIterations;
 
   // Support single exclude argument as string
diff --git a/src/modules/internet/index.ts b/src/modules/internet/index.ts
index 5eb9b4bc..8cc651a3 100644
--- a/src/modules/internet/index.ts
+++ b/src/modules/internet/index.ts
@@ -620,6 +620,7 @@ export class InternetModule extends ModuleBase {
           firstName + this.faker.helpers.arrayElement(['.', '_']) + lastName;
         break;
       case 2:
+      default:
         result = `${firstName}${this.faker.helpers.arrayElement([
           '.',
           '_',
@@ -804,6 +805,7 @@ export class InternetModule extends ModuleBase {
           firstName + this.faker.helpers.arrayElement(['.', '_']) + lastName;
         break;
       case 2:
+      default:
         result = `${firstName}${this.faker.helpers.arrayElement([
           '.',
           '_',
diff --git a/src/modules/person/index.ts b/src/modules/person/index.ts
index e0f4b6b0..0c5f79c3 100644
--- a/src/modules/person/index.ts
+++ b/src/modules/person/index.ts
@@ -1,5 +1,7 @@
 import type { Faker } from '../..';
+import { FakerError } from '../../errors/faker-error';
 import { ModuleBase } from '../../internal/module-base';
+import { assertLocaleData } from '../../locale-proxy';
 
 export enum Sex {
   Female = 'female',
@@ -18,6 +20,7 @@ export type SexType = `${Sex}`;
  * @param param2.generic Non-sex definitions.
  * @param param2.female Female definitions.
  * @param param2.male Male definitions.
+ * @param type Type of the definition.
  *
  * @returns Definition based on given sex.
  */
@@ -25,10 +28,14 @@ function selectDefinition<T>(
   faker: Faker,
   elementSelectorFn: (values: T[]) => string,
   sex: SexType | undefined,
-  // TODO @Shinigami92 2022-03-21: Remove fallback empty object when `strict: true`
-  { generic, female, male }: { generic?: T[]; female?: T[]; male?: T[] } = {}
+  {
+    generic,
+    female,
+    male,
+  }: { generic?: T[] | null; female?: T[] | null; male?: T[] | null },
+  type: string
 ): string {
-  let values: T[] | undefined;
+  let values: T[] | undefined | null;
 
   switch (sex) {
     case Sex.Female:
@@ -50,6 +57,8 @@ function selectDefinition<T>(
     } else {
       values = generic;
     }
+
+    assertLocaleData(values, `person.{${type}, female_${type}, male_${type}}`);
   }
 
   return elementSelectorFn(values);
@@ -92,11 +101,17 @@ export class PersonModule extends ModuleBase {
     const { first_name, female_first_name, male_first_name } =
       this.faker.rawDefinitions.person ?? {};
 
-    return selectDefinition(this.faker, this.faker.helpers.arrayElement, sex, {
-      generic: first_name,
-      female: female_first_name,
-      male: male_first_name,
-    });
+    return selectDefinition(
+      this.faker,
+      this.faker.helpers.arrayElement,
+      sex,
+      {
+        generic: first_name,
+        female: female_first_name,
+        male: male_first_name,
+      },
+      'first_name'
+    );
   }
 
   /**
@@ -135,16 +150,23 @@ export class PersonModule extends ModuleBase {
           generic: last_name_pattern,
           female: female_last_name_pattern,
           male: male_last_name_pattern,
-        }
+        },
+        'last_name_pattern'
       );
       return this.faker.helpers.fake(pattern);
     }
 
-    return selectDefinition(this.faker, this.faker.helpers.arrayElement, sex, {
-      generic: last_name,
-      female: female_last_name,
-      male: male_last_name,
-    });
+    return selectDefinition(
+      this.faker,
+      this.faker.helpers.arrayElement,
+      sex,
+      {
+        generic: last_name,
+        female: female_last_name,
+        male: male_last_name,
+      },
+      'last_name'
+    );
   }
 
   /**
@@ -164,11 +186,17 @@ export class PersonModule extends ModuleBase {
     const { middle_name, female_middle_name, male_middle_name } =
       this.faker.rawDefinitions.person ?? {};
 
-    return selectDefinition(this.faker, this.faker.helpers.arrayElement, sex, {
-      generic: middle_name,
-      female: female_middle_name,
-      male: male_middle_name,
-    });
+    return selectDefinition(
+      this.faker,
+      this.faker.helpers.arrayElement,
+      sex,
+      {
+        generic: middle_name,
+        female: female_middle_name,
+        male: male_middle_name,
+      },
+      'middle_name'
+    );
   }
 
   /**
@@ -305,11 +333,17 @@ export class PersonModule extends ModuleBase {
     const { prefix, female_prefix, male_prefix } =
       this.faker.rawDefinitions.person ?? {};
 
-    return selectDefinition(this.faker, this.faker.helpers.arrayElement, sex, {
-      generic: prefix,
-      female: female_prefix,
-      male: male_prefix,
-    });
+    return selectDefinition(
+      this.faker,
+      this.faker.helpers.arrayElement,
+      sex,
+      {
+        generic: prefix,
+        female: female_prefix,
+        male: male_prefix,
+      },
+      'prefix'
+    );
   }
 
   /**
@@ -350,9 +384,13 @@ export class PersonModule extends ModuleBase {
    * @since 8.0.0
    */
   jobDescriptor(): string {
-    return this.faker.helpers.arrayElement(
-      this.faker.definitions.person.title.descriptor
-    );
+    const values = this.faker.definitions.person.title.descriptor;
+
+    if (values == null) {
+      throw new FakerError('No person.title.descriptor definitions available.');
+    }
+
+    return this.faker.helpers.arrayElement(values);
   }
 
   /**
@@ -364,9 +402,13 @@ export class PersonModule extends ModuleBase {
    * @since 8.0.0
    */
   jobArea(): string {
-    return this.faker.helpers.arrayElement(
-      this.faker.definitions.person.title.level
-    );
+    const values = this.faker.definitions.person.title.level;
+
+    if (values == null) {
+      throw new FakerError('No person.title.area definitions available.');
+    }
+
+    return this.faker.helpers.arrayElement(values);
   }
 
   /**
@@ -378,9 +420,13 @@ export class PersonModule extends ModuleBase {
    * @since 8.0.0
    */
   jobType(): string {
-    return this.faker.helpers.arrayElement(
-      this.faker.definitions.person.title.job
-    );
+    const values = this.faker.definitions.person.title.job;
+
+    if (values == null) {
+      throw new FakerError('No person.title.job definitions available.');
+    }
+
+    return this.faker.helpers.arrayElement(values);
   }
 
   /**
diff --git a/src/modules/random/index.ts b/src/modules/random/index.ts
index 997583c1..474e8ca6 100644
--- a/src/modules/random/index.ts
+++ b/src/modules/random/index.ts
@@ -123,7 +123,7 @@ export class RandomModule extends ModuleBase {
       '_',
       '-',
     ];
-    let result: string;
+    let result = '';
 
     let iteration = 0;