fix(watch): post flush watchers should not fire when component is unmounted

fix #1603

packages/runtime-core/src/renderer.ts

@@ -2025,19 +2025,17 @@ function baseCreateRenderer(
     if (bum) {
       invokeArrayFns(bum)
     }
+    if (effects) {
+      for (let i = 0; i < effects.length; i++) {
+        stop(effects[i])
+      }
+    }
     // update may be null if a component is unmounted before its async
     // setup has resolved.
     if (update) {
       stop(update)
       unmount(subTree, instance, parentSuspense, doRemove)
     }
-    if (effects) {
-      queuePostRenderEffect(() => {
-        for (let i = 0; i < effects.length; i++) {
-          stop(effects[i])
-        }
-      }, parentSuspense)
-    }
     // unmounted hook
     if (um) {
       queuePostRenderEffect(um, parentSuspense)