fix: Don't show wildcard param completions

[jkciesluk]

fixes #4657

[jkciesluk]

There is still a similar issue in

List((1,2), (3,4)).map { (ab, _) =>
    @@
  }

We get completion x$1.

List((1,2), (3,4)).map { (ab, _) =>
    x$1
  }

It actually compiles, but this can be a bug in dotty. I will open an issue and add a link here

[tgodzik]

LGTM

I looked into whether we could check it a bit better, but it seems it's the most straightforward way.

[kubukoz]

that was quick!

I'm just curious, I thought completions for Scala 3 came from the compiler... can you give me some context on that?

[jkciesluk]

Most completions come from the compiler, but we add some more advanced ones, like completions for overriding methods, exhaustive match completion or completions for workspace symbols and extension methods (completions requiring adding an import) etc.