           </p>
 
           <ul>
-            {for line in @state.log
+            {for line, i in @state.log
               if line instanceof Error
-                <li style={color: 'red'}>{line.toString()}</li>
+                <li key={i} style={color: 'red'}>{line.toString()}</li>
               else
-                <li>{line}</li>}
+                <li key={i}>{line}</li>}
           </ul>
         </div>
       </Route>

          <table>
            <thead>
              <tr>
                {<th>{column}</th> for column in MANIFEST_COLUMNS}
                <th></th>
              </tr>
            </thead>

        </td>

        {for column in MANIFEST_COLUMNS[1...]
          <td key={column}>{metadata?[column] ? <span className="form-help">?</span>}</td>}

        <td>
          <button onClick={@removeSubjects.bind this, filenames...}>&times;</button>
