fix(mp): patch diffData

packages/vue-cli-plugin-uni/packages/mp-vue/dist/mp.runtime.esm.js

@@ -5420,6 +5420,8 @@ Vue.version = '2.6.11';
  */
 var ARRAYTYPE = '[object Array]';
 var OBJECTTYPE = '[object Object]';
+var NULLTYPE = '[object Null]';
+var UNDEFINEDTYPE = '[object Undefined]';
 // const FUNCTIONTYPE = '[object Function]'
 
 function diff(current, pre) {
@@ -5453,6 +5455,16 @@ function syncKeys(current, pre) {
     }
 }
 
+function nullOrUndefined(currentType, preType) {
+    if(
+        (currentType === NULLTYPE || currentType === UNDEFINEDTYPE) && 
+        (preType === NULLTYPE || preType === UNDEFINEDTYPE)
+    ) {
+        return false
+    }
+    return true
+}
+
 function _diff(current, pre, path, result) {
     if (current === pre) { return }
     var rootCurrentType = type(current);
@@ -5467,7 +5479,7 @@ function _diff(current, pre, path, result) {
                 var currentType = type(currentValue);
                 var preType = type(preValue);
                 if (currentType != ARRAYTYPE && currentType != OBJECTTYPE) {
-                    if (currentValue !== pre[key]) {
+                    if (currentValue !== pre[key] && nullOrUndefined(currentType, preType)) {
                         setResult(result, (path == '' ? '' : path + ".") + key, currentValue);
                     }
                 } else if (currentType == ARRAYTYPE) {