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>)
This suddenly popped up when editing some code - which wasn't relevant to the code fix (no
typein sight). But finding the brokenExactlyOneshould be enough to fix this.