refactor: add missing else in genNode (#8600)

src/compiler/codegen/index.js

@@ -435,7 +435,7 @@ function needsNormalization (el: ASTElement): boolean {
 function genNode (node: ASTNode, state: CodegenState): string {
   if (node.type === 1) {
     return genElement(node, state)
-  } if (node.type === 3 && node.isComment) {
+  } else if (node.type === 3 && node.isComment) {
     return genComment(node)
   } else {
     return genText(node)