Hide URL options for e2e blob: URL images

These won't work outside of the electron app so there is zero point
in trying to open them in an external browser or offerring to copy
them to the clipboard

electron_app/src/webcontents-handler.js

@@ -35,12 +35,15 @@ function onLinkContextMenu(ev, params) {
     const url = params.linkURL || params.srcURL;
 
     const popupMenu = new Menu();
+    // No point trying to open blob: URLs in an external browser: it ain't gonna work.
+    if (!url.startsWith('blob:')) {
         popupMenu.append(new MenuItem({
             label: url,
             click() {
                 safeOpenURL(url);
             },
         }));
+    }
 
     if (params.mediaType && params.mediaType === 'image' && !url.startsWith('file://')) {
         popupMenu.append(new MenuItem({
@@ -55,12 +58,15 @@ function onLinkContextMenu(ev, params) {
         }));
     }
 
+    // No point offerring to copy a blob: URL either
+    if (!url.startsWith('blob:')) {
         popupMenu.append(new MenuItem({
             label: 'Copy Link Address',
             click() {
                 clipboard.writeText(url);
             },
         }));
+    }
     // popup() requires an options object even for no options
     popupMenu.popup({});
     ev.preventDefault();