fix(reactivity): unwrap non-index accessed refs on reactive arrays (#1859)

close #1846

packages/reactivity/src/baseHandlers.ts

@@ -63,9 +63,10 @@ function createGetter(isReadonly = false, shallow = false) {
 
     const res = Reflect.get(target, key, receiver)
 
+    const keyIsSymbol = isSymbol(key)
     if (
-      isSymbol(key)
-        ? builtInSymbols.has(key)
+      keyIsSymbol
+        ? builtInSymbols.has(key as symbol)
         : key === `__proto__` || key === `__v_isRef`
     ) {
       return res
@@ -80,8 +81,12 @@ function createGetter(isReadonly = false, shallow = false) {
     }
 
     if (isRef(res)) {
-      // ref unwrapping, only for Objects, not for Arrays.
-      return targetIsArray ? res : res.value
+      // ref unwrapping - does not apply for Array + integer key.
+      const shouldUnwrap =
+        !targetIsArray ||
+        keyIsSymbol ||
+        '' + parseInt(key as string, 10) !== key
+      return shouldUnwrap ? res.value : res
     }
 
     if (isObject(res)) {