tweak user rendering in warning

in the RepoHeader when the event cannot be found

src/lib/components/repo/RepoHeader.svelte

@@ -48,7 +48,7 @@
       >
       {#if created_at === 0 && name.length === 0}
         <span class="text-xs text-warning">
-          cannot find referenced repository event by <UserHeader user={author} inline />
+          cannot find referenced repository event by <div class="badge bg-base-400 text-warning"><UserHeader user={author} inline size='xs'/></div>
         </span>    
       {/if}
     {/if}