useUnknownInCatchVariables would do much better to require ": unknown" rather than magically injecting it

🔎 Search Terms

useUnknownInCatchVariables

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about useUnknownInCatchVariables

⏯ Playground Link

No response

💻 Code

No response

🙁 Actual behavior

With useUnknownInCatchVariables :unknonw is magically injected after err (in catch (err))

try {
  console.log("in try")
}
catch (err) {
  console.log("in catch")
  console.log(err.message)
}

This results in a mysterious failure like so (from deno i.e. swc):

error: TS18046 [ERROR]: 'err' is of type 'unknown'.
    console.log(err.message)

The design of this option is very wrong, it's not worth the tiny saving of not having to type :unknown give how mysterious the above error is for a user who isn't aware of this option. It should have been designed to require this declaration rather than injecting it.

I realize this option can't be fixed at this point and it's probably not worth introducing a similar one with the better behavior. Perhaps as an alternative swc (and maybe other compilers) could be fixed to give an error that at least mentions useUnknownInCatchVariables.

🙂 Expected behavior

Something less mysterious :)

Additional information about the issue

None

The issue names the useUnknownInCatchVariables option and the TS18046 diagnostic. Begin by reviewing how that option produces the diagnostic in catch blocks. Done means the resulting behavior or error explains the option clearly, with the expected approach agreed.