[new feature] Image: add show-error prop (#3896)

src/image/test/__snapshots__/index.spec.js.snap

@@ -26,3 +26,5 @@ exports[`load event 2`] = `
 `;
 
 exports[`loading-placeholder prop 1`] = `<div class="van-image"><img class="van-image__img"></div>`;
+
+exports[`show-error prop 1`] = `<div class="van-image"></div>`;

src/image/test/index.spec.js

@@ -111,3 +111,16 @@ test('loading-placeholder prop', () => {
 
   expect(wrapper).toMatchSnapshot();
 });
+
+test('show-error prop', () => {
+  const wrapper = mount(Image, {
+    propsData: {
+      showError: false,
+      src: 'https://img.yzcdn.cn/vant/cat.jpeg'
+    }
+  });
+
+  wrapper.find('img').trigger('error');
+
+  expect(wrapper).toMatchSnapshot();
+});