Solves devlucky#159 check content type in fetch response

src/interceptors/fetchInterceptor.js

@@ -10,8 +10,13 @@ import { mapRequestInfoToUrlString, canUseWindow } from "../utils";
 
 const nativeFetch = canUseWindow && window.fetch;
 const fakeResponse = (response = {}, headers = {}) => {
-  const responseStr = JSON.stringify(response);
-  return new Response(responseStr, { headers });
+  // If content type exist and is different to application/json no parse the response
+  if (headers['content-type'] && headers['content-type'].indexOf('application/json') == -1) {
+    return new Response(response, { headers });
+  }
+
+  // Default handler, If no content type response as json.
+  return new Response(JSON.stringify(response), { headers });
 };
 
 export class FakeFetch {