v12 regression: explicitly annotated option return type with non-primative inner type causes compiler error

[illusionalsagacity]

Thank you for filing! Check list:

• Is it a bug? Usage questions should often be asked in the forum instead.
• Concise, focused, friendly issue title & description.
• A minimal, reproducible example.
• OS and browser versions, if relevant.
• Is it already fixed in master? Instructions

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If the explicit type annotation contains an array, result, dict, or Null.t (I haven't tried exhaustively) it results in a compiler error when the function is called. This doesn't seem to happen with primative types however.

let foo = (): option<array<string>> => Some(["foo"])

let bar = foo()

results in

Type Errors
[E] Line 3, column 10:
This function has type unit => option<array>
It only accepts 1 argument; here, it's called with more.

[illusionalsagacity]

I looked around for where a reproduction test case ought to be placed in the repo, but it's a bit unclear to me. Where should these kinds of regression test cases go?

[cristianoc]

A link to the playground is more than enough.