Return module to pool on regex.Close()

[max-hoffman]

privateRegex.Close()'s error handling was circumventing returning the module back to the pool. I don't understand the code well enough to know whether the other error handling logic is correct, but even in the error case I imagine we want to return the module objects to the pool.

[Hydrocharged]

This is fine, but it won’t fix the issue. Modifying the code such that there’s a single module (without the pool altogether) still has the memory leak, albeit slower. This will help my mentioned PR reclaim memory faster in the event of an error, but it doesn’t solve the issue.