Handle Alert exception on notification failure

[karwosts]

Proposed change

Currently when Alert integration attemps to send a notification, it will throw an unhandled exception if any of its notifiers do not exist. This can happen in two situations:

1. On home assistant boot, the alert may attempt to fire before all notifiers have been created.
2. If user specifies one or more notifiers that do not exist in the configuration.

When this happens the alert gets into a bad state, where its internal self._firing flag is set, but it throws an exception before it can call async_write_ha_state. Because of a notification failure, even though the watched condition may be true, the alert does not update its state to on. It will forever remain in idle state if any notifications cannot be delivered.

This change adds a simple try/catch around each attempt to send notification. This ensures that even if one notification fails, the Alert state is always accurate, and all other notifiers that could receive the notification continue to do so.

If the failure was due to trying to send a notification on boot before a notifier was setup, that notifier will then continue receiving subsequent notifications at the original repeat interval.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes Alert remains "On" but otherwise idle if a notifier fails #59742, fixes Alert can't find notifiers if skip_first: false and alert condition is set on start #52606
• This PR is related to issue:
• Link to documentation pull request:

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[home-assistant]

Hey there @home-assistant/core, @frenck, mind taking a look at this pull request as it has been labeled with an integration (alert) you are listed as a code owner for? Thanks!

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[edenhaus]

Thanks @karwosts.

Can you please rebase your PR and fix the merge conflicts. Thanks :)

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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[karwosts]

Change has been rebased/merged.

[edenhaus]

Thanks @karwosts 👍