idempotent close

[comods]

Is there a performance reason for WebSocket.close() to throw an error if called twice?

If not, it would be nice to have it idempotent by becoming a no-op instead of throwing an error.
This would save us from always wrapping WebSocket.close() in a try/catch block.

[ghost]

This implementation is not written using a garbage collector so closing a socket releases it. Therefore you need to track this and update whatever data structures you have when you close. The error you get is really just a fallback emergency break to warn you your code is broken. You shouldn't use try catch ideally you should fix your usage.

Remember - this library is written in C and C has a different memory management philosophy which does not use garbage collection.