Fix exception when QueryValues is not provided

(for example on homepage)

iwm_browser/templates/searchBar.html

@@ -1,7 +1,9 @@
 <div class='searchBar'>
     <form action="/search" method="get">
         <div class="search_entry">
-            {% set QueryValues = "" if not QueryValues %}
+            {% if not QueryValues %}
+                {% set QueryValues = "" %}
+            {% endif %}
             <input type='text' id="q" name="q" value='{{ QueryValues["q"] if QueryValues["q"] is not none }}' placeholder="Enter a level name or code"/>
             <button class="searchButton" id='searchButton' type='submit'>🔍</button>
         </div>