Compatibility with previous versions. highestIndex will be added automatically

Author: sylvainjule

index.js

@@ -72,6 +72,9 @@ export default {
                 this.localValue = value
             }
         },
+    },
+    created() {
+
     },
     computed: {
         languages() {
@@ -102,7 +105,7 @@ export default {
             return !this.limit || !this.localValue || !this.localValue.length || this.localValue.length < this.limit
         },
         highestIndex() {
-            return this.exists ? this.localValue[0].highestIndex : 0
+            return this.exists ? this.localValue[0].highestIndex || Math.max.apply(Math, this.localValue.map((item) => item.panelIndex)) : 0
         },
         newIndex() {
             return this.highestIndex + 1