Use unique keys in suggestion v-for

vue/Navigation/FilterBar/Input.vue

@@ -18,9 +18,14 @@
       <a class="dropdown-item" v-if="isLoading">
         <em>Loading…</em>
       </a>
+      <!--
+        The displayed suggestion string is not unique, and the keys can be anything,
+        not just strings, so we just use JSON to ensure all keys are strings
+        to avoid VUe warnings about duplicate keys in v-for.
+      -->
       <a
         v-for="[key, suggestion] in filteredSuggestions"
-        :key="suggestion"
+        :key="JSON.stringify(key)"
         v-on:click.stop="select(key, true)"
         :title="suggestion"
         :class="{ 'selected': key === current }"