Small fixes

Author: eregon

src/main/java/org/truffleruby/core/module/ModuleNodes.java

@@ -381,14 +381,11 @@ public AliasKeywordNode(RubyNode newName, RubyNode oldName) {
 
         @Override
         public Object execute(VirtualFrame frame) {
-            final RubyModule module = RubyArguments.getDeclarationContext(frame).getModuleToDefineMethods();
+            var module = RubyArguments.getDeclarationContext(frame).getModuleToDefineMethods();
 
             final Object newNameObject = newName.execute(frame);
             final Object oldNameObject = oldName.execute(frame);
 
-            assert newNameObject instanceof RubySymbol;
-            assert oldNameObject instanceof RubySymbol;
-
             RubySymbol newNameSymbol = (RubySymbol) newNameObject;
             RubySymbol oldNameSymbol = (RubySymbol) oldNameObject;
             return AliasMethodNode.aliasMethod(module, newNameSymbol, oldNameSymbol, this);