fix hint for initializer w no references

vyper/semantics/analysis/module.py

@@ -507,7 +507,7 @@ def visit_InitializesDecl(self, node):
 
             if rhs is None:
                 hint = f"try importing {item.alias} first"
-            elif isinstance(module_ref, vy_ast.NamedExpr):
+            elif not isinstance(module_ref.parent, vy_ast.Subscript):
                 hint = f"did you mean {module_ref.id}[{lhs} := {rhs}]?"
             else:
                 hint = f"add `{lhs} := {rhs}` to its initializer list"