Carousel: Fix onChange emit value (#16705)

packages/carousel/src/main.vue

@@ -148,7 +148,9 @@ export default {
 
     activeIndex(val, oldVal) {
       this.resetItemPosition(oldVal);
-      this.$emit('change', val, oldVal);
+      if (oldVal > -1) {
+        this.$emit('change', val, oldVal);
+      }
     },
 
     autoplay(val) {