No warning for malformed erlang_ls.config file

[alanz]

Describe the bug

The logic for loading erlang_ls.config files is to take a list of locations, attempt to load from them in order, until one succeeds.

It does not distinguish between a file not existing, and one existing but having a YAML syntax error in it.

So making a typo in your config can cause it to load a completely different config file.

Expected behavior

I would expect it to report a diagnostic for the first config file it finds, if it has a syntax error in it.

Context

• erlang_ls version (tag/sha): 8ff322fddcf162ed0af494704fd9fd31b3ed3268

[alanz]

There are two cases here

• the first config file found in the path does not parse a valid yaml
• the first config file found in the search path has invalid config.

Examples of invalid config are trying to enable/disable lenses that do not exist.

[alanz]

A related issue would be if there is a config file specified, but it does not exist.

I think the logic for that should be

• Absolute path: complain if not found
• non-absolute path: append it to the root path, complain if not found

The current search logic includes tagging a non-absolute path onto all the possible config file locations. I think this is too loose, and likely to result in unexpected and hard to debug results.