Guard thread access to avoid crash.
We've consistently had a crash related to mutations of playerItemObservers as one of our top 4-5 issues. It looks like the paths leading to mutation of playerItemObservers can come from arbitrary threads (I was able to capture it combing from both the main thread and another thread, for example). The change in this PR shipped in our latest couple releases and seems to have resolved the issue!
Lemme know if you'd like any more information or clarification! Thanks for making this library.
Here are some samples of the crashes we were seeing along with the drop-off after this change was deployed.
appreciate the help @timonus
My pleasure!