fix commit bugs

app/views/admin/assets/_asset.html.erb

@@ -10,8 +10,8 @@
 			</ul>
 		</div>
 	</td>
-	<td><%= asset.data.file.content_type %></td>
-	<td><%= number_to_human_size(asset.data.file.file_length) %></td>
+	<td><%= asset.data.file.content_type rescue nil %></td>
+	<td><%= number_to_human_size(asset.data.file.file_length) rescue nil %></td>
 	<td><%= asset.description rescue nil %></td>
 	<td>
 		<div class="label-group">