added no source story to symbol thumbail

Author: JesmoDev

packages/uui-symbol-file-thumbnail/lib/uui-symbol-file-thumbnail.story.ts

@@ -11,11 +11,22 @@ export default {
 
 export const Overview: Story = props =>
   html`<uui-symbol-file-thumbnail
-    style="max-width: 300px;"
+    style="max-width: 300px; max-height: 300px"
     src=${props.src}
     alt=${props.alt}></uui-symbol-file-thumbnail>`;
 
 Overview.args = {
   src: 'https://picsum.photos/300/200',
   alt: 'Image alt',
 };
+
+export const NoSource: Story = props =>
+  html`<uui-symbol-file-thumbnail
+    style="max-width: 300px; max-height: 300px"
+    src=${props.src}
+    alt=${props.alt}></uui-symbol-file-thumbnail>`;
+
+NoSource.args = {
+  src: '',
+  alt: 'Image alt',
+};