Guard clauses prior to event listeners that may not be present

Author: matt-bernhardt

app/javascript/filters.js

@@ -3,6 +3,12 @@ function initFilterToggle() {
   var filter_toggle = document.getElementById('filter-toggle');
   var filter_panel = document.getElementById('filter-container');
   var filter_categories = document.getElementsByClassName('filter-category');
+
+  // No need for event listeners if filters aren't present.
+  if (!filter_toggle || !filter_panel) {
+    return;
+  }
+
   filter_toggle.addEventListener('click', event => {
     filter_panel.classList.toggle('hidden-md');
     filter_toggle.classList.toggle('expanded');

app/javascript/search_form.js

@@ -68,11 +68,11 @@ if (Array.from(allPanels).includes(geoboxPanel && geodistancePanel)) {
     togglePanelState(geodistancePanel);
   });
 
-  document.getElementById('advanced-summary').addEventListener('click', () => {
+  document.getElementById('advanced-summary')?.addEventListener('click', () => {
     togglePanelState(advancedPanel);
   });
 } else {
-  document.getElementById('advanced-summary').addEventListener('click', () => {
+  document.getElementById('advanced-summary')?.addEventListener('click', () => {
     togglePanelState(advancedPanel);
   });
 }