fix(tests): look for json in thrown error (#8601)

integration-tests/json-output.test.ts

@@ -55,9 +55,27 @@ describe('JSON output', () => {
 
     expect(thrown).toBeDefined();
     const message = (thrown as Error).message;
-    const jsonStart = message.indexOf('{');
+
-    expect(jsonStart).toBeGreaterThan(-1);
+    // Use a regex to find the first complete JSON object in the string
-    const payload = JSON.parse(message.slice(jsonStart));
+    const jsonMatch = message.match(/{[\s\S]*}/);
+
+    // Fail if no JSON-like text was found
+    expect(
+      jsonMatch,
+      'Expected to find a JSON object in the error output',
+    ).toBeTruthy();
+
+    let payload;
+    try {
+      // Parse the matched JSON string
+      payload = JSON.parse(jsonMatch![0]);
+    } catch (parseError) {
+      console.error('Failed to parse the following JSON:', jsonMatch![0]);
+      throw new Error(
+        `Test failed: Could not parse JSON from error message. Details: ${parseError}`,
+      );
+    }
+
     expect(payload.error).toBeDefined();
     expect(payload.error.type).toBe('Error');
     expect(payload.error.code).toBe(1);