When remote debugging is turned on, underlying error in promise rejection causes: NSError RCTJSONStringify: Invalid type in JSON write (NSError)

Issue Description

Some native modules such as NSFileManager return an NSError that has an underlying NSError in the userInfo dictionary. React native handles this fine out of the box, but when the remote debugger is turned on, the websocket message sender chokes on attempting to stringify the second NSError into json.

I’m happy to help fix this, first time contributing so any pointers are welcome.

Steps to Reproduce / Code Snippets

I’ve posted a repository with the minimal reproduction case here https://github.com/superseriouscompany/react-native-error-repro

The steps are: first, turn on remote debugging. Then implement the following code:

// objc
RCT_EXPORT_METHOD(triggerError:(NSString *)foo
                  resolver:(RCTPromiseResolveBlock)resolve
                  rejecter:(RCTPromiseRejectBlock)reject)
{
  NSError *underlyingError = [NSError errorWithDomain:@"underlyingDomain" code:419 userInfo:nil];
  NSError *err = [NSError errorWithDomain:@"domain" code:68 userInfo:@{@"NSUnderlyingError": underlyingError}];

  reject(@"foo", @"bar", err);
}

// js
triggerError('anything').catch(err => { console.log(err)})

Expected Results

error is logged to console, execution continues.

Actual Results

### Additional Information - React Native version: 0.35.0 - Platform(s) (iOS, Android, or both?): iOS - Operating System (macOS, Linux, or Windows?): macOS

[fungilation]

I’m still hitting a similar error:

RCTJSONStringify() encountered the following error: Invalid type in JSON write (NSURL)

With NSURL in brackets instead.

I haven’t been hitting this error until I upgraded RN from 0.37 to 0.41.

[miklschmidt]

Okay, in my case it seems to be the AppTransportSecurityPolicy (or whatever it’s called) that wasn’t set to allow insecure connections. I had to hack RTCUtils.m:82 to print the JSON blob instead of the error. It seems like the userInfo object is the cause of the issue.