fix: silentJSONParsing=false should throw on invalid JSON (#7253) (#7257)

Co-authored-by: Rudransh Gupta <rudranshgupta@Rudranshs-MacBook-Pro.local>
Co-authored-by: Jay <jasonsaayman@gmail.com>

lib/defaults/index.js

@@ -108,7 +108,7 @@ const defaults = {
 
     if (data && utils.isString(data) && ((forcedJSONParsing && !this.responseType) || JSONRequested)) {
       const silentJSONParsing = transitional && transitional.silentJSONParsing;
-      const strictJSONParsing = !silentJSONParsing && JSONRequested;
+      const strictJSONParsing = !silentJSONParsing;
 
       try {
         return JSON.parse(data, this.parseReviver);
@@ -158,4 +158,4 @@ utils.forEach(['delete', 'get', 'head', 'post', 'put', 'patch'], (method) => {
   defaults.headers[method] = {};
 });
 
-export default defaults;
+export default defaults;

test/regression_silent_json.js

@@ -0,0 +1,69 @@
+
+import assert from 'assert';
+import axios from '../index.js';
+
+describe('Regression: Silent JSON Parsing', function () {
+
+    beforeEach(function () {
+        // Mock adapter to return invalid JSON
+        axios.defaults.adapter = async (config) => {
+            return {
+                data: '{ invalid json }',
+                status: 200,
+                statusText: 'OK',
+                headers: {},
+                config
+            };
+        };
+    });
+
+    afterEach(function () {
+        delete axios.defaults.adapter;
+    });
+
+    it('should throw SyntaxError when silentJSONParsing is false', async function () {
+        try {
+            await axios.get('/test', {
+                transitional: {
+                    silentJSONParsing: false
+                }
+            });
+            assert.fail('Should have thrown error');
+        } catch (err) {
+            assert.ok(err.name === 'SyntaxError' || err.code === 'ERR_BAD_RESPONSE', 'Error should be SyntaxError or ERR_BAD_RESPONSE');
+        }
+    });
+
+    it('should return raw string when silentJSONParsing is true (default)', async function () {
+        const response = await axios.get('/test', {
+            transitional: {
+                silentJSONParsing: true
+            }
+        });
+        assert.strictEqual(response.data, '{ invalid json }');
+    });
+
+    it('should throw SyntaxError when responseType is json (legacy behavior)', async function () {
+        try {
+            await axios.get('/test', {
+                responseType: 'json',
+                transitional: {
+                    silentJSONParsing: false
+                }
+            });
+            assert.fail('Should have thrown error');
+        } catch (err) {
+            assert.ok(err.name === 'SyntaxError' || err.code === 'ERR_BAD_RESPONSE', 'Error should be SyntaxError or ERR_BAD_RESPONSE');
+        }
+    });
+
+    it('should swallow error when silentJSONParsing is true and responseType is json (legacy behavior)', async function () {
+        const response = await axios.get('/test', {
+            responseType: 'json',
+            transitional: {
+                silentJSONParsing: true
+            }
+        });
+        assert.strictEqual(response.data, '{ invalid json }');
+    });
+});