Ignore invalid display config files and boot normally.

[tarek-y-ismail]

Closes #3628

Adds a new exception type StaticDsiplayConfig::InvalidConfig, which is now used inside YamlFileDisplayConfig::load_config to signal a failure in parsing. When this exception is caught, we skip the rest of config parsing and the remaining code that depends on it and run as if --display-config=static=path/to/invalid/file.display was not provided.

[Saviq]

Let's make the new behaviour optional (off by default)?

Keep the current constructor so we don't break ABI, but add a new one with a bool exit_on_error=true?

This way, Frame we can make to start up regardless of display config issues.

Also, in StaticDisplayConfig we could then log an error for the less critical bits and ignore / use defaults for that particular element rather than bail completely.

[AlanGriffiths]

Just a note that I'm against the resolution suggested in the issue. (This implements that resolution: I'm not against the implementation)

[Saviq]

As discussed on the bug, maybe having a special case (and that could be default) for the file being empty would also do.

[AlanGriffiths]

Let's make the new behaviour optional (off by default)?

+1

Keep the current constructor so we don't break ABI, but add a new one with a bool exit_on_error=true?

Or use the "named constructor" idiom: StaticDisplayConfig:on_errors_use_default() is clearer than StaticDisplayConfig{true}/StaticDisplayConfig{false}

This way, Frame we can make to start up regardless of display config issues.

I'm still not convinced this is desirable

[AlanGriffiths]

Also, we should have tests

[tarek-y-ismail]

Also, we should have tests

Lucky for me, we already do (the ones failing right now :)). I'll see if I can add any.

[AlanGriffiths]

We decided on another approach