[BUG] Getting "websocket: internal error, unexpected bytes at end of flate stream" despite protecting write calls with mutex

[NeonWizard]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

I've been getting "websocket: internal error, unexpected bytes at end of flate stream" followed by the socket becoming unwriteable. From looking at the other issue in this repo, it looks like this might happen when simultaneously writing to the same connection. However, in my application I've protected Write calls with a mutex. What other scenarios can cause this? Are there race conditions in the library, such as with WriteControl?

Expected Behavior

Should not be getting these errors.

Steps To Reproduce

It happens rarely, it's not able to be consistently reproduced.

Anything else?

No response