fix(queue-view): improve handling of falsy job.id values

Fixes #181.

src/server/views/dashboard/templates/queueJobsByState.hbs

@@ -93,17 +93,17 @@
               <input class="js-bulk-job" name="jobChecked" type="checkbox" />
             </div>
 
-            <a role="button" data-toggle="collapse" href="#collapse{{hashIdAttr this.id}}">
+            <a role="button" data-toggle="collapse" href="#collapse{{hashIdAttr this}}">
               <h4 class="header-collapse">
-                <span class="label label-default">{{ this.id }}</span>
+                <span class="label label-default">{{#if this.id}}{{ this.id }}{{else}}<em>missing id</em>{{/if}}</span>
                 {{#if this.data.name}}
                   <span style="margin-left: 8px">{{ this.data.name }}</span>
                 {{else if this.name}}
                   <span style="margin-left: 8px">{{ this.name }}</span>
                 {{/if}}
               </h4>
             </a>
-            <div id="collapse{{hashIdAttr this.id}}" class="collapse">
+            <div id="collapse{{hashIdAttr this}}" class="collapse">
               {{~> dashboard/jobDetails this basePath=../basePath displayJobInline=true queueName=../queueName queueHost=../queueHost jobState=../state }}
             </div>
           </li>

src/server/views/helpers/handlebars.js

@@ -14,6 +14,9 @@ const replacer = (key, value) => {
   }
 };
 
+// For jobs that don't have a valid ID, produce a random ID we can use in its place.
+const idMapping = new WeakMap();
+
 const helpers = {
   json(obj, pretty = false) {
     const args = [obj, replacer];
@@ -44,8 +47,17 @@ const helpers = {
     block.push(options.fn(this));
   },
 
-  hashIdAttr(id) {
-    return crypto.createHash('sha256').update(id).digest('hex');
+  hashIdAttr(obj) {
+    const { id } = obj;
+    if (typeof id === 'string') {
+      return crypto.createHash('sha256').update(id).digest('hex');
+    }
+    let mapping = idMapping.get(obj);
+    if (!mapping) {
+      mapping = crypto.randomBytes(32).toString('hex');
+      idMapping.set(obj, mapping);
+    }
+    return mapping;
   },
 };