Factory failure drains available connection max from pool

[randall-fulton]

Issue

If the provided factory returns an error, the pool's total connection limit will permanently decrease by one. Provided this happens enough times, the pool can become deadlocked, with zero capacity.

Here is a playground example of the issue: https://go.dev/play/p/lAy0_uoKMFj

Notice after the first two failures (the number of max connections in the pool) the errors change, due to the pool itself never being able to attempt to fetch new connections.

Expected Outcome

When the factory fails, the reserved slot in the pool should be returned to the pool.

[randall-fulton]

Working on a fix for this now.

[buraksezer]

Thank you for your contribution @randall-fulton