Don't throw in GetMetadataReference for an unexpected assembly type (#40794)

src/Compilers/CSharp/Portable/Compilation/CSharpCompilation.cs

@@ -1118,7 +1118,12 @@ public new MetadataReference GetMetadataReference(IAssemblySymbol assemblySymbol
 
         private protected override MetadataReference CommonGetMetadataReference(IAssemblySymbol assemblySymbol)
         {
-            return GetMetadataReference(assemblySymbol.EnsureCSharpSymbolOrNull(nameof(assemblySymbol)));
+            if (assemblySymbol is Symbols.PublicModel.AssemblySymbol { UnderlyingAssemblySymbol: var underlyingSymbol })
+            {
+                return GetMetadataReference(underlyingSymbol);
+            }
+
+            return null;
         }
 
         internal MetadataReference GetMetadataReference(AssemblySymbol assemblySymbol)

src/Compilers/CSharp/Test/Symbol/Compilation/CompilationAPITests.cs

@@ -2267,6 +2267,20 @@ public void GetMetadataReferenceAPITest()
             Assert.NotNull(reference2);
         }
 
+        [Fact]
+        [WorkItem(40466, "https://github.com/dotnet/roslyn/issues/40466")]
+        public void GetMetadataReference_VisualBasicSymbols()
+        {
+            var comp = CreateCompilation("");
+
+            var vbComp = CreateVisualBasicCompilation("", referencedAssemblies: TargetFrameworkUtil.GetReferences(TargetFramework.Standard));
+            var assembly = (IAssemblySymbol)vbComp.GetBoundReferenceManager().GetReferencedAssemblies().First().Value;
+
+            Assert.Null(comp.GetMetadataReference(assembly));
+            Assert.Null(comp.GetMetadataReference(vbComp.Assembly));
+            Assert.Null(comp.GetMetadataReference((IAssemblySymbol)null));
+        }
+
         [Fact]
         public void ConsistentParseOptions()
         {

src/Compilers/VisualBasic/Portable/Compilation/VisualBasicCompilation.vb

@@ -1232,7 +1232,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         End Function
 
         Private Protected Overrides Function CommonGetMetadataReference(assemblySymbol As IAssemblySymbol) As MetadataReference
-            Return GetMetadataReference(assemblySymbol.EnsureVbSymbolOrNothing(Of AssemblySymbol)(NameOf(assemblySymbol)))
+            Dim symbol = TryCast(assemblySymbol, AssemblySymbol)
+            If symbol IsNot Nothing Then
+                Return GetMetadataReference(symbol)
+            End If
+
+            Return Nothing
         End Function
 
         Public Overrides ReadOnly Property ReferencedAssemblyNames As IEnumerable(Of AssemblyIdentity)

src/Compilers/VisualBasic/Test/Semantic/Compilation/CompilationAPITests.vb

@@ -2257,6 +2257,19 @@ End Class
             Assert.NotNull(reference2)
         End Sub
 
+        <WorkItem(40466, "https://github.com/dotnet/roslyn/issues/40466")>
+        <Fact>
+        Public Sub GetMetadataReference_CSharpSymbols()
+            Dim comp As Compilation = CreateCompilation("")
+
+            Dim csComp = CreateCSharpCompilation("", referencedAssemblies:=TargetFrameworkUtil.GetReferences(TargetFramework.Standard))
+            Dim assembly = csComp.GetBoundReferenceManager().GetReferencedAssemblies().First().Value
+
+            Assert.Null(comp.GetMetadataReference(DirectCast(assembly.GetISymbol(), IAssemblySymbol)))
+            Assert.Null(comp.GetMetadataReference(csComp.Assembly))
+            Assert.Null(comp.GetMetadataReference(Nothing))
+        End Sub
+
 
         <Fact()>
         Public Sub EqualityOfMergedNamespaces()