Select: fix a wrong variable name (#10618)

packages/select/src/select.vue

@@ -364,7 +364,7 @@
           if (!this.multiple) {
             if (this.selected) {
               if (this.filterable && this.allowCreate &&
-                this.createdSelected && this.createdOption) {
+                this.createdSelected && this.createdLabel) {
                 this.selectedLabel = this.createdLabel;
               } else {
                 this.selectedLabel = this.selected.currentLabel;