Only remove callback when a tag handle was succesfully created.

[timyhac]

No description provided.

[timyhac]

@kyle-github - this is the method that is used to tear down the tag either explicitly or implicitly by the garbage collector.

Previously, this code was checking that neither removing the event callback, nor destroying the tag, returned an error code, and if so would throw an exception. I'm not sure if there are any valid reasons for return an error code (other than bugs in the wrapper or core library), and I believe there is no recourse if either fail.

The new code fixes the bug that was there (found in #432) and also ignores any other errors that might occur.

Your thoughts?

[iancolledge]

I can't thank you enough for not throwing that exception in the destructor. It was the source of many issues in live running systems when thrown from the finalizer invocation by the garbage collector thread. As you probably know exceptions from the GC thread are awful and cannot be handled like normal exceptions.
We think the source of the bug is either in the locking in the c lib, or the hashtable implementation only scanning 10 location ahead to deal with collisions. Either way it's gone now hopefully, but we're a bit worried if it's due the 10 iterations limit in the C lib there may be tags hanging around that never get cleaned up. We did some memory monitoring and it can't be that many. I raised a request for a method to query the hashtable size, but understand if you don't want to implement this. For now we will just restart our processes once a month.