chore: use smart eqeqeq check

Author: ST-DDT

src/faker.ts

@@ -114,7 +114,7 @@ export class Faker {
         Object.defineProperty(this.definitions[moduleName], entryName, {
           get: () => {
             const localizedModule = this.locales[this.locale][moduleName];
-            if (typeof localizedModule?.[entryName] === 'undefined') {
+            if (localizedModule?.[entryName] == null) {
               // certain localization sets contain less data then others.
               // in the case of a missing definition, use the default localeFallback
               // to substitute the missing set data