Fix arg with null location (microsoft#1220)

Author: jakebailey

src/Analysis/Ast/Impl/Analyzer/Evaluation/ExpressionEval.cs

@@ -63,8 +63,7 @@ public ExpressionEval(IServiceContainer services, IPythonModule module, GlobalSc
         public LocationInfo GetLocationInfo(Node node) => node?.GetLocation(Module) ?? LocationInfo.Empty;
 
         public Location GetLocationOfName(Node node) {
-            node = node ?? throw new ArgumentNullException(nameof(node));
-            if (Module.ModuleType != ModuleType.User && Module.ModuleType != ModuleType.Library) {
+            if (node == null || (Module.ModuleType != ModuleType.User && Module.ModuleType != ModuleType.Library)) {
                 return DefaultLocation;
             }