Fix NullReferenceException in FailFast handling

src/Compilers/Core/Portable/InternalUtilities/FailFast.cs

@@ -65,11 +65,10 @@ internal static void DumpStackTrace(Exception? exception = null, string? message
             if (exception is object)
             {
                 Console.WriteLine("Exception info");
-                for (Exception? current = exception; current is object; current = current!.InnerException)
+                for (Exception? current = exception; current is object; current = current.InnerException)
                 {
                     Console.WriteLine(current.Message);
                     Console.WriteLine(current.StackTrace);
-                    current = current.InnerException;
                 }
             }