If a controller is V1 but it has a messaging system, subscribe to its stateChange event

Author: MajorLift

packages/composable-controller/src/ComposableController.ts

@@ -166,6 +166,12 @@ export class ComposableController extends BaseController<
    * @param controller - Controller instance to update
    */
   #updateChildController(controller: ControllerInstance): void {
+    if (!isBaseController(controller) && !isBaseControllerV1(controller)) {
+      throw new Error(
+        'Invalid controller: controller must extend from BaseController or BaseControllerV1',
+      );
+    }
+
     const { name } = controller;
     if (isBaseControllerV1(controller)) {
       controller.subscribe((childState) => {
@@ -174,7 +180,11 @@ export class ComposableController extends BaseController<
           [name]: childState,
         }));
       });
-    } else if (isBaseController(controller)) {
+    }
+    if (
+      (isBaseControllerV1(controller) && 'messagingSystem' in controller) ||
+      isBaseController(controller)
+    ) {
       this.messagingSystem.subscribe(
         `${name}:stateChange`,
         (childState: StateConstraint) => {
@@ -184,10 +194,6 @@ export class ComposableController extends BaseController<
           }));
         },
       );
-    } else {
-      throw new Error(
-        'Invalid controller: controller must extend from BaseController or BaseControllerV1',
-      );
     }
   }
 }