fix(core): more detailed error message when version cannot be found

[amorscher]

When running a lerna command and no version is present in lerna.json configuration following error message is printed:

lerna ERR! ENOLERNA `lerna.json` does not exist, have you run `lerna init`?

As described in (#3311) this is not completely correct.

Description

Addtional check is added during command validation to prove a version is available in lerna.json file. In addition the check for having a lerna configuration (lerna.json) available is adapted to really check for existance of the config file. This is achieved by setting an additional flag configNotFound in the project object during lerna.json retrival.

Motivation and Context

Improve error messages for invalid lerna.json to support user finding configuration problems.
The issue is described here (#3311).

How Has This Been Tested?

Added a unit test.
Manually built a lerna version.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (change that has absolutely no effect on users)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[amorscher]

@JamesHenry any chance that the fix will make it to main?

Thx for having a look!

[JamesHenry]

Obviously I can't speak to the intent behind this comment originally, but your change does make it seem a little nonsensical, given you are adding an isEmpty right below a comment saying "no need to distinguish between missing and empty".

We could probably just amend the this.configNotFound assignment to check for Object.keys(loaded.config ?? {}).length === 0?

[amorscher]

You are right that is a little bit weird. For this case i think I need to distinguish btw. emtpy and notFound because in case of empty the error message of no lerna version should appear.
The comment is related to the following line assigning an emtpy object to config. This make completly sense there because doing this avoids nasty if checks. I changed the flag from empty to noConfigFound and return it in the config. Hope this makes it a little bit less nonsensical and understandable. What do you think?

[JamesHenry]

.

[JamesHenry]

Thanks @amorscher!