Default values in workflows seem to work.

frontend/src/js/page/wb-launch-workflow-page.js

@@ -58,6 +58,12 @@ function uuidsToCwl(obj, isFile) {
   throw Error('Expected Arvados path or array of paths');
 }
 
+function parseKeepRef(value) {
+  if (typeof(value) === 'object' && 'location' in value && value.location.startsWith('keep:'))
+    return value.location.substr(5);
+  return value;
+}
+
 class WBPathDisplay extends Component {
   fetchData() {
     const { app, path } = this.props;
@@ -72,6 +78,7 @@ class WBPathDisplay extends Component {
       item: xhr.response,
       tail: path.substr(m[0].length)
     }));
+    prom = prom.catch(() => this.setState({ 'error': 'Cannot load' }));
   }
 
   componentDidMount() {
@@ -83,7 +90,10 @@ class WBPathDisplay extends Component {
     this.fetchData();
   }
 
-  render({}, { item, tail }) {
+  render({}, { item, tail, error }) {
+    if (error)
+      return error;
+
     if (!item)
       return 'Loading...';
 
@@ -180,12 +190,12 @@ class WBLaunchWorkflowPage extends Component {
             <ul class="mb-0">
               { value.map(path => (
                 <li>
-                  <WBPathDisplay app={ app } path={ path } />
+                  <WBPathDisplay app={ app } path={ parseKeepRef(path) } />
                 </li>
               )) }
             </ul>
         ) : (
-          <WBPathDisplay app={ app } path={ value } />
+          <WBPathDisplay app={ app } path={ parseKeepRef(value) } />
         ) : null }
       </div>
     );