fix(types): wrong void return type of multiGet (#767)

Fix #764

Author: mtt87

src/AsyncStorage.native.ts

@@ -269,7 +269,7 @@ const AsyncStorage = ((): AsyncStorageStatic => {
         reject: null as any,
       };
 
-      const promiseResult = new Promise<readonly KeyValuePair[] | void>(
+      const promiseResult = new Promise<readonly KeyValuePair[]>(
         (resolve, reject) => {
           getRequest.resolve = resolve;
           getRequest.reject = reject;

src/types.ts

@@ -23,7 +23,7 @@ export type MultiRequest = {
   keys: readonly string[];
   callback?: MultiGetCallback;
   keyIndex: number;
-  resolve?: (result?: readonly KeyValuePair[]) => void;
+  resolve?: (result: readonly KeyValuePair[]) => void;
   reject?: (error?: any) => void;
 };
 
@@ -125,7 +125,7 @@ export type AsyncStorageStatic = {
   multiGet: (
     keys: string[],
     callback?: MultiGetCallback
-  ) => Promise<readonly KeyValuePair[] | void>;
+  ) => Promise<readonly KeyValuePair[]>;
 
   /**
    * Use this as a batch operation for storing multiple key-value pairs. When