fix(vSlot): handle non-comment children when extracting slot key

Author: edison1105

packages/compiler-vapor/src/transforms/vSlot.ts

@@ -90,12 +90,17 @@ function transformComponentSlot(
 
   let slotKey
   if (isTransitionNode(node) && nonSlotTemplateChildren.length) {
-    const keyProp = findProp(
-      nonSlotTemplateChildren[0] as ElementNode,
-      'key',
-    ) as VaporDirectiveNode
-    if (keyProp) {
-      slotKey = keyProp.exp
+    const nonCommentChild = nonSlotTemplateChildren.find(
+      n => n.type !== NodeTypes.COMMENT,
+    )
+    if (nonCommentChild) {
+      const keyProp = findProp(
+        nonCommentChild as ElementNode,
+        'key',
+      ) as VaporDirectiveNode
+      if (keyProp) {
+        slotKey = keyProp.exp
+      }
     }
   }