[4.0] Redis Caching fails ungracefully when server down, or incorrectly configured.

[PhilETaylor]

Steps to reproduce the issue

Joomla 4.0-dev

Correctly configure caching to a redis server. Reload any Joomla page - see it caches and no issues.

Turn off the redis server OR edit /configuration.php and change

public $redis_server_host = 'yourredisserver.com';
to
public $redis_server_host = 'redisDOWN';

reload the /administrator/ url

Expected result

Joomla handles this failure with grace.

Joomla doesn't display any Notices or Warnings.

Actual result

[wilsonge]

Fix for the undefined variable notice #31121

I'm not really sure if there's a way to catch the php warnings that get thrown (it's the same in the session driver too for that part)

[wilsonge]

Ok i think I'm going to close this as a won't fix.

And more in line of technically it's very tricky without underlying redis driver changes to fix this than because I don't want to.

[wilsonge]

If anyone does come up with a solution more than happy to consider it clearly. But without a concrete suggestion hard to see how to take this forward