Enable typescript strictNullChecks

prisma/seeder.ts

@@ -67,6 +67,12 @@ export class Seeder {
   async generateLog(): Promise<void> {
     const packageVersion = await getInstalledPackageVersion('idn-area-data');
 
+    if (!packageVersion) {
+      throw new Error(
+        'idn-area-data package is not installed. Make sure to run `pnpm install` first.',
+      );
+    }
+
     await this.prisma.seederLogs.create({
       data: { dataVersion: packageVersion },
     });

src/app.module.ts

@@ -22,8 +22,8 @@ import { VillageModule } from './village/village.module';
       inject: [ConfigService],
       useFactory: (config: ConfigService) => [
         {
-          ttl: seconds(config.get('APP_THROTTLE_TTL')),
-          limit: config.get('APP_THROTTLE_LIMIT'),
+          ttl: seconds(config.get('APP_THROTTLE_TTL') as number),
+          limit: config.get('APP_THROTTLE_LIMIT') as number,
           skipIf: () => config.get('APP_ENABLE_THROTTLE') !== 'true',
         },
       ],

src/common/config/app.ts

@@ -27,11 +27,13 @@ export type AppConfig = {
 export const appConfig: AppConfig = {
   env: (process.env.APP_ENV as AppConfig['env']) || 'dev',
   host: process.env.APP_HOST || '0.0.0.0',
-  port: Number.parseInt(process.env.APP_PORT) || 3000,
+  port: Number.parseInt(process.env.APP_PORT || '3000'),
   pagination: {
-    maxPageSize:
-      Number.parseInt(process.env.APP_PAGINATION_MAX_PAGE_SIZE) || 100,
-    defaultPageSize:
-      Number.parseInt(process.env.APP_PAGINATION_DEFAULT_PAGE_SIZE) || 10,
+    maxPageSize: Number.parseInt(
+      process.env.APP_PAGINATION_MAX_PAGE_SIZE || '100',
+    ),
+    defaultPageSize: Number.parseInt(
+      process.env.APP_PAGINATION_DEFAULT_PAGE_SIZE || '10',
+    ),
   },
 } as const;

src/common/decorator/EqualsAny.ts

@@ -29,14 +29,14 @@ export function EqualsAny(
 @ValidatorConstraint({ name: 'equalsAny' })
 export class EqualsAnyConstraint implements ValidatorConstraintInterface {
   validate(value: any, args?: ValidationArguments): boolean {
-    const [validValues] = args.constraints as [string[], any];
+    const [validValues] = (args?.constraints ?? []) as [string[], any];
     return typeof value === 'string' && validValues.includes(value);
   }
 
   defaultMessage(validationArguments?: ValidationArguments): string {
-    const { constraints, property } = validationArguments;
+    const { constraints, property } = validationArguments ?? {};
     return `${property} must equals one of these: ${(
-      constraints[0] as string[]
+      (constraints?.[0] as string[] | undefined) ?? []
     ).join(', ')}.`;
   }
 }

src/common/decorator/IsNotSymbol.ts

@@ -31,7 +31,7 @@ export function IsNotSymbol(
 @ValidatorConstraint({ name: 'isNotSymbol' })
 export class IsNotSymbolConstraint implements ValidatorConstraintInterface {
   validate(value: any, args?: ValidationArguments): boolean {
-    const [allowedSymbols = ''] = args.constraints as [string, any];
+    const [allowedSymbols = ''] = (args?.constraints ?? []) as [string, any];
     const safeAllowedSymbols = allowedSymbols
       .split('')
       .map((s) => `\\${s}`)
@@ -42,7 +42,7 @@ export class IsNotSymbolConstraint implements ValidatorConstraintInterface {
   }
 
   defaultMessage(validationArguments?: ValidationArguments): string {
-    const { constraints, property } = validationArguments;
+    const { constraints, property } = validationArguments ?? {};
     const [allowedSymbols = ''] = constraints as [string, any];
 
     return allowedSymbols

src/common/decorator/api-data-response.decorator.ts

@@ -72,9 +72,7 @@ export const ApiDataResponse = <Model extends Type<any>>(
             type: 'object',
             nullable: options.multiple ? undefined : true,
             properties: {
-              total: options.multiple
-                ? { type: 'number', example: 1 }
-                : undefined,
+              total: options.multiple ? { type: 'number', example: 1 } : {},
             },
           },
         },

src/common/utils/coordinate.ts

@@ -44,11 +44,15 @@ export const convertCoordinate = (coordinate: string): number[] => {
     throw new Error('Invalid coordinate format');
   }
 
-  const [a, b, c, d, e, f] = coordinate.match(/[0-9,\.]+/g);
-  const [y, x] = coordinate.match(/(N|S|E|W)/g);
+  const degrees = coordinate.match(/[0-9,\.]+/g);
+  const polars = coordinate.match(/(N|S|E|W)/g);
 
-  const latitude = calculate(a, b, c, y);
-  const longitude = calculate(d, e, f, x);
+  if (!degrees || !polars) {
+    throw new Error('Invalid coordinate format');
+  }
+
+  const [a, b, c, d, e, f] = degrees;
+  const [y, x] = polars;
 
-  return [latitude, longitude];
+  return [calculate(a, b, c, y), calculate(d, e, f, x)]; // [latitude, longitude]
 };

src/common/utils/db/index.ts

@@ -36,5 +36,9 @@ export const validateDBConfig = (...vars: (keyof typeof dbConfig)[]) => {
  * Get the database provider features, based on the current config.
  */
 export const getDBProviderFeatures = (): DBProviderFeatures | undefined => {
+  if (!dbConfig.provider) {
+    return undefined;
+  }
+
   return dbProviderConfig[dbConfig.provider]?.features;
 };

src/district/district.service.spec.ts

@@ -173,10 +173,10 @@ describe('DistrictService', () => {
       const testCode = '110101';
       const expectedDistrict = districts.find((d) => d.code === testCode);
       const expectedRegency = regencies.find(
-        (r) => r.code === expectedDistrict.regencyCode,
+        (r) => r.code === expectedDistrict?.regencyCode,
       );
       const expectedProvince = provinces.find(
-        (p) => p.code === expectedRegency.provinceCode,
+        (p) => p.code === expectedRegency?.provinceCode,
       );
 
       const findUniqueSpy = vitest

src/island/island.service.spec.ts

@@ -223,12 +223,12 @@ describe('IslandService', () => {
   describe('findByCode', () => {
     it('should return an island', async () => {
       const testCode = '110140001';
-      const expectedIsland = islands.find((i) => i.code === testCode);
+      const expectedIsland = islands.find((i) => i.code === testCode) as Island;
       const expectedRegency = regencies.find(
-        (r) => r.code === expectedIsland.regencyCode,
+        (r) => r.code === expectedIsland?.regencyCode,
       );
       const expectedProvince = provinces.find(
-        (p) => p.code === expectedRegency.provinceCode,
+        (p) => p.code === expectedRegency?.provinceCode,
       );
 
       const findUniqueSpy = vitest
@@ -259,10 +259,10 @@ describe('IslandService', () => {
 
     it('should return an island without regency', async () => {
       const testCode = '120040001';
-      const expectedIsland = islands.find((i) => i.code === testCode);
+      const expectedIsland = islands.find((i) => i.code === testCode) as Island;
       const expectedProvince = provinces.find(
         (p) => p.code === testCode.slice(0, 2),
-      );
+      ) as Province;
 
       const findUniqueIslandSpy = vitest
         .spyOn(prismaService.island, 'findUnique')

src/island/island.service.ts

@@ -81,11 +81,11 @@ export class IslandService {
         ...this.addDecimalCoordinate(island),
         parent: {
           regency: null,
-          province: await this.prisma.province.findUnique({
+          province: (await this.prisma.province.findUnique({
             where: {
               code: code.slice(0, 2),
             },
-          }),
+          })) as NonNullable<IslandWithParent['parent']['province']>,
         },
       };
     }

src/main.ts

@@ -18,7 +18,7 @@ async function bootstrap() {
   // Init API documentation with Swagger.
   const docConfig = new DocumentBuilder()
     .setTitle('Indonesia Area API')
-    .setVersion(process.env.npm_package_version)
+    .setVersion(process.env.npm_package_version as string)
     .setDescription(
       'API that provides information about Indonesia administrative area.',
     )

src/province/province.service.spec.ts

@@ -130,7 +130,8 @@ describe('ProvinceService', () => {
   describe('findByCode', () => {
     it('should return a province when given a valid code', async () => {
       const testCode = '11';
-      const expectedProvince = provinces.find((p) => p.code === testCode);
+      const expectedProvince =
+        provinces.find((p) => p.code === testCode) ?? null;
 
       const findUniqueSpy = vitest
         .spyOn(prismaService.province, 'findUnique')

tsconfig.json

@@ -12,7 +12,7 @@
     "baseUrl": "./",
     "incremental": true,
     "skipLibCheck": true,
-    "strictNullChecks": false,
+    "strictNullChecks": true,
     "noImplicitAny": false,
     "strictBindCallApply": false,
     "forceConsistentCasingInFileNames": false,