Fix additional syntaxes page issues

Fixes an exception that occurred when there were no search results
Fixes the search bar overlapping the title on smaller width displays

Author: APickledWalrus

src/components/syntaxes/SyntaxDisplayManager.astro

@@ -455,8 +455,10 @@ export interface VersionFilterData {
 
         // prepare sidebar
         updateSidebar();
-        scrollEndObserver.observe(filteredItems[0].element);
-        scrollEndObserver.observe(filteredItems[filteredItems.length - 1].element);
+        if (filteredItems.length > 1) {
+            scrollEndObserver.observe(filteredItems[0].element);
+            scrollEndObserver.observe(filteredItems[filteredItems.length - 1].element);
+        }
 
         // show message when no results found
         if (filteredItems.length === 0) {

src/pages/syntaxes/[...id].astro

@@ -159,6 +159,10 @@ const sidebarEntries = syntaxes.map(syntax => ({
     }
     :global(div.header) {
         grid-template-columns: minmax(0, calc(var(--sl-sidebar-width) - var(--sl-nav-pad-x) - var(--sl-nav-gap))) 1fr auto;
+        justify-content: start;
+    }
+    :global(.title-wrapper) { /* ensure title is not covered by search */
+        min-width: fit-content;
     }
 
     #syntaxes-wrapper {