fix(reactivity): check skip first before checking ref when creating observer (#12813)

fix #12812

Author: gilnatab

src/core/observer/index.ts

@@ -7,7 +7,6 @@ import {
   hasOwn,
   isArray,
   hasProto,
-  isObject,
   isPlainObject,
   isPrimitive,
   isUndef,
@@ -108,23 +107,21 @@ export function observe(
   shallow?: boolean,
   ssrMockReactivity?: boolean
 ): Observer | void {
-  if (!isObject(value) || isRef(value) || value instanceof VNode) {
-    return
+  if (value && hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
+    return value.__ob__
   }
-  let ob: Observer | void
-  if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
-    ob = value.__ob__
-  } else if (
+  if (
     shouldObserve &&
     (ssrMockReactivity || !isServerRendering()) &&
     (isArray(value) || isPlainObject(value)) &&
     Object.isExtensible(value) &&
     !value.__v_skip /* ReactiveFlags.SKIP */ &&
-    !rawMap.has(value)
+    !rawMap.has(value) &&
+    !isRef(value) &&
+    !(value instanceof VNode)
   ) {
-    ob = new Observer(value, shallow, ssrMockReactivity)
+    return new Observer(value, shallow, ssrMockReactivity)
   }
-  return ob
 }
 
 /**