AddMissingEqualsToTypeDefinitionCodeFixProvider crash

[0101]

This suddenly popped up when editing some code - which wasn't relevant to the code fix (no type in sight). But finding the broken ExactlyOne should be enough to fix this.

System.ArgumentException : The input sequence contains more than one element.
Parameter name: source
   at Microsoft.FSharp.Collections.SeqModule.ExactlyOne[T](IEnumerable`1 source)
   at async StartupCode$FSharp-Editor(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.VisualStudio.FSharp.Editor.CodeFixExtensions.CodeFixContext-RegisterFsharpFix@85(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.CodeFixes.CodeFixService.GetCodeFixesAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformFunctionAsync[T](<Unknown Parameters>)

[vzarytovskii]

Yeah, as a rule of thumb, we should not be throwing in vs, but instead reporting errors using built-in mechanism

[psfinaki]

Repro:

let f x = 
    match x with
    | _ ->
        let _ = [
            x with
        ]

repro.mp4

Indeed, we have two different FS0010 here: