Minor bug - fatal error in psr16 adapter if an exception is thrown

[MaximilianKresse]

Proposed changes

There is an minor bug in the psr16 adapter, the couchdb driver and the mongodb driver.

You throw multiple exceptions with code "NULL". But this will trigger a fatal error in strict mode: https://3v4l.org/fimJH

Types of changes

What types of changes does your code introduce to Phpfastcache?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves an existing code/behavior)
• Deprecated third party dependency update
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation/Typo/Resource update that does not involve any code modification

Agreement

I have read the CONTRIBUTING and CODING GUIDELINE docs

[Geolim4]

oO how that thing could pass the tests ?
Thanks you for the PR !!