Description

At some point all code running queries start failing with the following error: undefined is not an object (evaluating 'v.next'). I'm sorry I don't have a stack trace, the the user that sent this log basically got this error from everywhere a realm query was looped over, and ultimately ended up in a hard crash: EXC_BAD_ACCESS: Attempted to dereference garbage pointer 0x1c.

I got error logs from 3 different places in the app that run queries asynchronously / with timers or in a loop. They all happened at almost the same time while looping through collections.

Code example that threw the error:

// Query 1
let res = realm.objects('QueueItem').filtered(`groupId=${groupId}`);

res = res
  .sorted([
    ['locked', false],
    ['error', false],
    ['mobile', true],
    ['priority', false],
    ['added', false],
  ])
  .slice(0, count)
  .map((obj) => {
    let res = toPlainObject(obj);
    return res;
  });

return res;


// query 2 in a completely different location in the code
let items = realm
      .objects('GalleryItem')
      .filtered(`added <= ${timestamp} and webId != null`);
for (let ele of items)....


// Helper func
export function toPlainObject(realmObject, schemaProperties) {
  let res = {};
  for (let k of Object.keys(schemaProperties)) {
    res[k] = realmObject[k];
  }
  return res;
}

Stacktrace & log output

Only the error message is available as our logging handles the unhandled exception and only logs the message.

Can you reproduce a bug?

Not yet

Reproduction Steps

Unknown. Just filtering, querying and looping.

Version

10.20.0-alpha.2

What SDK flavour are you using?

Local Database only

Are you using encryption?

No, not using encryption

Platform OS and version(s)

iOS 14.4.2 (iPhone XR)