fix assigning value to type

src/codegen.zig

@@ -2056,6 +2056,7 @@ pub const CodeGen = struct {
                 }
                 return null;
             }
+            return self.emitErrorFmt("cannot assign non-type value to Type variable '{s}'", .{name});
         }
 
         // Union reassignment: s = .circle(3.14) or s = .none