refactor: Simplify deepMerge function and improve type checking (#2151)

.changeset/curvy-pants-confess.md

@@ -0,0 +1,5 @@
+---
+"@thirdweb-dev/react-native": patch
+---
+
+improve typechecking for deepMerge function

packages/react-native/src/evm/i18n/strings.ts

@@ -36,7 +36,6 @@ export const getLocale = (
   return deepMerge(defaultLocale, locale);
 };
 
-
 export const en = (locale?: DeepPartial<LocaleType>) => getLocale("en", locale);
 export const es = (locale?: DeepPartial<LocaleType>) => getLocale("es", locale);
 export const ja = (locale?: DeepPartial<LocaleType>) => getLocale("ja", locale);

packages/react-native/src/evm/types/deepPartial.ts

@@ -2,21 +2,24 @@ export type DeepPartial<T> = {
   [P in keyof T]?: DeepPartial<T[P]>;
 };
 
-export function deepMerge<T>(target: T, source: DeepPartial<T>): T {
+export function deepMerge<T>(target: T, source: DeepPartial<T> = {}): T {
   for (const key in source) {
+    if (!source.hasOwnProperty(key)) {
+      continue;
+    }
     if (
-      source[key] instanceof Object &&
-      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-      // @ts-ignore
-      key in target &&
-      target[key] instanceof Object
+      isObject(target) &&
+      target.hasOwnProperty(key) &&
+      isObject(target[key])
     ) {
-      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-      // @ts-ignore
       deepMerge(target[key], source[key]);
     } else {
-      target[key] = source[key] as any;
+      target[key] = source[key] as (typeof target)[typeof key];
     }
   }
   return target;
 }
+
+function isObject(obj: any): obj is object {
+  return obj !== null && typeof obj === "object";
+}