Undefined typing of parameters in generated function

[SamCheung2]

What are the steps to reproduce this issue?

1. npm i

What happens?

Some Generated functions are given " | undefined " due to a '?' in the parameters causing typescript errors in the ESLint.
example:
const build(id? : string){}

What were you expecting to happen?

Before it would not generate the '?'
…

Any logs, error output, etc?

…

Any other comments?

Issue was caused by this push: v6.25.0...v6.26.0
Error on build: v6.26.0
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What versions are you using?

Operating System: Mac/Windows
Package Version: v6.26.0
Browser Version: ...