test by hardcoding nullability in script files

Author: baronfel

src/FsAutoComplete.Core/CompilerServiceInterface.fs

@@ -367,7 +367,7 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize, parallelRefe
       )
 
       let allFlags =
-        Array.append [| "--targetprofile:netstandard" |] fsiAdditionalArguments
+        Array.append [| "--targetprofile:netstandard"; "--checknulls+"; "--define:NULLABLE" |] fsiAdditionalArguments
 
       let! (opts, errors) =
         checker.GetProjectOptionsFromScript(

src/FsAutoComplete.Core/SignatureFormatter.fs

@@ -43,11 +43,7 @@ module SignatureFormatter =
   let rec formatFSharpType (context: FSharpDisplayContext) (typ: FSharpType) : string =
     let context = context.WithPrefixGenericParameters()
 
-    let nullabilityClause =
-      if typ.HasNullAnnotation || typ.IsNullAmbivalent then
-        " | null"
-      else
-        ""
+    let nullabilityClause = if typ.HasNullAnnotation then " | null" else ""
 
     try
       if typ.IsTupleType || typ.IsStructTupleType then