fix: ElementPlusError: [ElOnlyChild] no valid child node found

src/components/scWorkflow/nodes/addNode.vue

@@ -3,7 +3,7 @@
 		<div class="add-node-btn">
 			<el-popover placement="right-start" :width="270" trigger="click" :hide-after="0" :show-after="0">
 				<template #reference>
-					<el-button v-if="!disabled" type="primary" icon="plus" circle></el-button>
+					<el-button v-show="!disabled" type="primary" icon="plus" circle></el-button>
 				</template>
 				<div class="add-node-popover-body">
 					<ul>