Fix some JS issues

public/assets/index.js

@@ -14,13 +14,16 @@
                 "class_name": "grid gap-4 grid-cols-2 prose-img:m-0"
             });
 
+            const mediaForm = document.getElementById("media_form");
+            if (mediaForm !== null) {
                 htmx.on('#media_form', 'htmx:xhr:progress', function (evt) {
                     htmx.find('#progress').setAttribute('value', evt.detail.loaded / evt.detail.total * 100)
                 });
+            }
         });
 
     const mapContainer = document.getElementById("map");
-    if (mapContainer !== undefined) {
+    if (mapContainer !== null) {
         document.getElementById("go-back").addEventListener("click", () => {
           history.back();
         });