fix: indent rule looking for a node out of range

[fguitton]

Hello,

This PR focuses on the correction of a recurring bug triggering :

Cannot read property 'loc' of undefined

Fixes #14538
Fixes #13957
Fixes #13956
Fixes #11023

Many more ...

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[X] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofix to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

What changes did you make? (Give an overview)

Added check on the length of the node.declarations array.

Is there anything you'd like reviewers to focus on?

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Florian Guitton (37ab6b3)

[mdjermanovic]

Hi @fguitton, thanks for the PR!

As described in the issues you linked, the cause of this problem is that @typescript-eslint/parser allows invalid syntax. The problem will be fixed in @typescript-eslint/parser (typescript-eslint/typescript-eslint#1852).

I'm not in favor of updating rules to account for invalid syntax, because the root cause will eventually be fixed in the parser.

This particular problem in the indent rule doesn't seem critical to me since there's an easy workaround described in #14538 (comment).

@eslint/eslint-tsc thoughts?

[btmills]

I tend to agree. The core AST traversal and especially rules themselves rely on the parser to have already caught any invalid syntax.

[nzakas]

Agreed