Considering requiring all config files to exist (and be valid) in the config manager

[llucax]

What's needed?

The ConfigManagingActor takes a list of configuration paths, but requires only one of them to exist.

This seems to make sense considering new files read override what old files had, as this means some files will be used as overrides, and if one doesn't want to override anything from a previous file, it seems logical to not have the file at all.

When starting up, this seems OK ish, we could assume missing files are OK, but once a file was present, it would be weird that is removed, and in updates we would need to keep track of which files were successfully read at least once to determine if a missing file is an error or not.

In any case, we are always guessing. Sometimes it could be a more likely guess than in other cases, but it is always a guess.

Proposed solution

Require that ALL specified config paths are present and valid. This can lead to a more cumbersome setup (as one might need to create empty files) but makes things very explicit, and we can always treat issues reading or parsing config files as errors.

Additional context

Coming from:

• Fix ConfigManagingActor raising unhandled exceptions when file doesn't exist #1116 (comment)

Also mentioned here:

• Fix ConfigManagingActor raising unhandled exceptions when file doesn't exist #1116 (comment)