Fixes #20026

[remojansen]

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Fixes #20026

[mhegazy]

i do not think we should duplicate the function implementation here. consider passing the new error messages as optional arguments to checkNullExpression instead.

[remojansen]

@mhegazy thanks for the code review. I just sent a new commit that uses optional arguments instead of a new function.

[remojansen]

Hi @mhegazy I just resolved some merge conflicts. Is there anything else that I can do to speed up merging this PR into master? Thanks!

[mhegazy]

Sorry for the delay, can you please update your PR.

[remojansen]

@mhegazy thanks for merging the PR, can you please explain to me what was that timeout error in the build?

src/harness/parallel/worker.ts:58:17 - error TS2322: Type 'string | number' is not assignable to type 'number'.
  Type 'string' is not assignable to type 'number'.

58                 timeout = n;
                   ~~~~~~~


src/harness/parallel/worker.ts:130:17 - error TS2322: Type 'string | number' is not assignable to type 'number'.
  Type 'string' is not assignable to type 'number'.

130                 timeout = n;
                    ~~~~~~~


jake aborted.
Error: ENOENT: no such file or directory, unlink 'built/local/run.js'
    at Object.fs.unlinkSync (fs.js:1061:18)
    at Exec.<anonymous> (/home/rjansen/CODE/TypeScript/Jakefile.js:417:16)

I would like to learn about it future contributions. Thanks!

[mhegazy]

@types/mocha changed, and we needed to respond to that. see #21075 for more details.