1 files changed, 55 insertions, 50 deletions

diff --git a/main.js b/main.js
index 9840746..8d95f5b 100644
--- a/main.js
+++ b/main.js
@@ -3663,9 +3663,9 @@ const infoMetadataAccordions = [];
     });
     const btn = document.getElementById('map-legend-button');
     if (Object.values(STYLES).some((v) => Object.values(v).some((v2) => v2 != null))) {
-      btn.classList.remove('disabled');
+      btn?.classList.remove('disabled');
     } else {
-      btn.classList.add('disabled');
+      btn?.classList.add('disabled');
     }
   };
   const onClickFunction = function(layerList, event) {
@@ -4213,21 +4213,23 @@ const infoMetadataAccordions = [];
   })();
 
   const button_menu = document.getElementById('measure-button')
-    .getElementsByTagName('button')[0];
-  button_menu.addEventListener('click', function(event) {
-    if (event.currentTarget.getAttribute('aria-expanded') === 'true') {
-      disposePopover();
-      setup(getMeasureMode());
-    } else {
-      setup(null);
-      /* XXX workaround for https://github.com/twbs/bootstrap/issues/41005#issuecomment-2585390544 */
-      const activeElement = document.activeElement;
-      if (activeElement.isEqualNode(btn_close)) {
-          activeElement.blur();
+    ?.getElementsByTagName('button')?.[0];
+  if (button_menu != null) {
+    button_menu.addEventListener('click', function(event) {
+      if (event.currentTarget.getAttribute('aria-expanded') === 'true') {
+        disposePopover();
+        setup(getMeasureMode());
+      } else {
+        setup(null);
+        /* XXX workaround for https://github.com/twbs/bootstrap/issues/41005#issuecomment-2585390544 */
+        const activeElement = document.activeElement;
+        if (activeElement.isEqualNode(btn_close)) {
+            activeElement.blur();
+        }
       }
-    }
-  });
-  btn_close.onclick = () => button_menu.click();
+    });
+    btn_close.onclick = () => button_menu.click();
+  }
 })();
 
 /* popup and feature overlays */
@@ -5422,9 +5424,9 @@ const disposePopover = (function() {
   header.appendChild(btnClose);
 
   const measureButton = document.getElementById('measure-button')
-    .getElementsByTagName('button')[0];
+    ?.getElementsByTagName('button')?.[0];
   MAP.on('singleclick', function(event) {
-    if (measureButton.getAttribute('aria-expanded') === 'true') {
+    if (measureButton?.getAttribute('aria-expanded') === 'true') {
       /* skip popover while measuring */
       return;
     }
@@ -6028,40 +6030,43 @@ const ageFilterSetActive = (function() {
     modal.hide();
   };
 
-  const btn = document.getElementById('age-filter-button').getElementsByTagName('button')[0];
-  if (ageFilterSettings.active) {
-    btn.classList.replace('btn-light', 'btn-dark');
-  }
-  panel.addEventListener('show.bs.modal', function() {
-    backdrop.classList.add('modal-backdrop', 'show');
-    btn.setAttribute('aria-expanded', 'true');
-    btn.classList.replace('btn-light', 'btn-dark');
-  });
-  panel.addEventListener('hide.bs.modal', function() {
-    /* XXX workaround for https://github.com/twbs/bootstrap/issues/41005#issuecomment-2585390544 */
-    const activeElement = document.activeElement;
-    if (activeElement instanceof HTMLElement) {
-        activeElement.blur();
-    }
-  });
-  panel.addEventListener('hidden.bs.modal', function() {
-    if (!ageFilterSettings.active) {
-      btn.classList.replace('btn-dark', 'btn-light');
-    }
-    if (updateHelpTextTimeoutID != null) {
-      clearTimeout(updateHelpTextTimeoutID);
-      updateHelpTextState.value = null;
-      updateHelpTextTimeoutID = null;
+  const btn = document.getElementById('age-filter-button')
+    ?.getElementsByTagName('button')?.[0];
+  if (btn != null) {
+    if (ageFilterSettings.active) {
+      btn.classList.replace('btn-light', 'btn-dark');
     }
-    btn.setAttribute('aria-expanded', 'false');
-    backdrop.classList.remove('modal-backdrop', 'show');
-  });
+    panel.addEventListener('show.bs.modal', function() {
+      backdrop.classList.add('modal-backdrop', 'show');
+      btn.setAttribute('aria-expanded', 'true');
+      btn.classList.replace('btn-light', 'btn-dark');
+    });
+    panel.addEventListener('hide.bs.modal', function() {
+      /* XXX workaround for https://github.com/twbs/bootstrap/issues/41005#issuecomment-2585390544 */
+      const activeElement = document.activeElement;
+      if (activeElement instanceof HTMLElement) {
+          activeElement.blur();
+      }
+    });
+    panel.addEventListener('hidden.bs.modal', function() {
+      if (!ageFilterSettings.active) {
+        btn.classList.replace('btn-dark', 'btn-light');
+      }
+      if (updateHelpTextTimeoutID != null) {
+        clearTimeout(updateHelpTextTimeoutID);
+        updateHelpTextState.value = null;
+        updateHelpTextTimeoutID = null;
+      }
+      btn.setAttribute('aria-expanded', 'false');
+      backdrop.classList.remove('modal-backdrop', 'show');
+    });
 
-  btn.onclick = function() {
-    disposePopover();
-    dialog_setup();
-    modal.show();
-  };
+    btn.onclick = function() {
+      disposePopover();
+      dialog_setup();
+      modal.show();
+    };
+  }
 
   return (function() { /* setter for ageFilterSettings.active */
     let timeoutID = null;