[Payment due @sobitneupane] Account for null values in prepareRequestPayload

jest/setup.ts

@@ -288,7 +288,7 @@ jest.mock('@libs/prepareRequestPayload/index.native.ts', () => ({
         for (const key of Object.keys(data)) {
             const value = data[key];
 
-            if (value === undefined) {
+            if (value === undefined || value === null) {
                 continue;
             }
 

src/libs/prepareRequestPayload/index.native.ts

@@ -16,7 +16,7 @@ const prepareRequestPayload: PrepareRequestPayload = (command, data, initiatedOf
         promiseChain = promiseChain.then(() => {
             const value = data[key];
 
-            if (value === undefined) {
+            if (value === undefined || value === null) {
                 return Promise.resolve();
             }
 

src/libs/prepareRequestPayload/index.ts

@@ -10,7 +10,7 @@ const prepareRequestPayload: PrepareRequestPayload = (command, data) => {
     for (const key of Object.keys(data)) {
         const value = data[key];
 
-        if (value === undefined) {
+        if (value === undefined || value === null) {
             continue;
         }
 

tests/unit/prepareRequestPayloadTest.ts

@@ -0,0 +1,40 @@
+import prepareRequestPayload from '@libs/prepareRequestPayload';
+
+describe('prepareRequestPayload', () => {
+    it('should append string values to FormData', async () => {
+        const formData = await prepareRequestPayload('TestCommand', {authToken: 'abc123', email: 'test@example.com'}, false);
+
+        expect(formData.get('authToken')).toBe('abc123');
+        expect(formData.get('email')).toBe('test@example.com');
+    });
+
+    it('should omit null values from FormData instead of coercing them to the string "null"', async () => {
+        const formData = await prepareRequestPayload('TestCommand', {authToken: null, email: null, referer: 'ecash'}, false);
+
+        expect(formData.has('authToken')).toBe(false);
+        expect(formData.has('email')).toBe(false);
+        expect(formData.get('referer')).toBe('ecash');
+    });
+
+    it('should omit undefined values from FormData', async () => {
+        const formData = await prepareRequestPayload('TestCommand', {authToken: undefined, platform: 'web'}, false);
+
+        expect(formData.has('authToken')).toBe(false);
+        expect(formData.get('platform')).toBe('web');
+    });
+
+    it('should include falsy non-null/undefined values (0, false, empty string)', async () => {
+        const formData = await prepareRequestPayload('TestCommand', {count: 0, flag: false, label: ''}, false);
+
+        expect(formData.get('count')).toBe('0');
+        expect(formData.get('flag')).toBe('false');
+        expect(formData.get('label')).toBe('');
+    });
+
+    it('should return an empty FormData for an empty data object', async () => {
+        const formData = await prepareRequestPayload('TestCommand', {}, false);
+        const entries = Array.from(formData.entries());
+
+        expect(entries).toHaveLength(0);
+    });
+});