fix(compiler-sfc): transform empty srcset w/ includeAbsolute: true (#13639)

close vitejs/vite-plugin-vue#631

packages/compiler-sfc/__tests__/__snapshots__/templateTransformSrcset.spec.ts.snap

@@ -16,6 +16,16 @@ export function render(_ctx, _cache) {
 }"
 `;
 
+exports[`compiler sfc: transform srcset > transform empty srcset w/ includeAbsolute: true 1`] = `
+"import { openBlock as _openBlock, createElementBlock as _createElementBlock } from "vue"
+
+const _hoisted_1 = { srcset: " " }
+
+export function render(_ctx, _cache) {
+  return (_openBlock(), _createElementBlock("img", _hoisted_1))
+}"
+`;
+
 exports[`compiler sfc: transform srcset > transform srcset 1`] = `
 "import { createElementVNode as _createElementVNode, Fragment as _Fragment, openBlock as _openBlock, createElementBlock as _createElementBlock } from "vue"
 import _imports_0 from './logo.png'

packages/compiler-sfc/__tests__/templateTransformSrcset.spec.ts

@@ -72,6 +72,14 @@ describe('compiler sfc: transform srcset', () => {
     ).toMatchSnapshot()
   })
 
+  test('transform empty srcset w/ includeAbsolute: true', () => {
+    expect(
+      compileWithSrcset(`<img srcset=" " />`, {
+        includeAbsolute: true,
+      }).code,
+    ).toMatchSnapshot()
+  })
+
   test('transform srcset w/ stringify', () => {
     const code = compileWithSrcset(
       `<div>${src}</div>`,

packages/compiler-sfc/src/template/transformSrcset.ts

@@ -71,6 +71,7 @@ export const transformSrcset: NodeTransform = (
 
           const shouldProcessUrl = (url: string) => {
             return (
+              url &&
               !isExternalUrl(url) &&
               !isDataUrl(url) &&
               (options.includeAbsolute || isRelativeUrl(url))