chore(Lactose): await user existence check in AssetController.Create

Lactose/Controllers/AssetController.cs

@@ -366,16 +366,17 @@ public class AssetController(
     /// Creates a new asset record.
     /// </summary>
     /// <param name="dto">The asset creation data.</param>
+    /// <param name="cancellationToken">Token to cancel the operation.</param>
     /// <returns>200 with the new asset ID, or an error response.</returns>
     [NonAction]
     [HttpPut]
     [Authorize(Roles = "Curator,Admin")]
-    public ActionResult<Guid> Create([FromBody] AssetCreateDto dto) {
+    public async Task<ActionResult<Guid>> Create([FromBody] AssetCreateDto dto, CancellationToken cancellationToken) {
         var uid         = authService.GetUserData(User)?.Id;
         var accesslevel = authService.GetUserData(User)!.AccessLevel;
 
         if (dto.UploadedBy.HasValue) {
-            if (userRepository.Find(dto.UploadedBy.Value) == null) {
+            if (await userRepository.FindAsync(dto.UploadedBy.Value, cancellationToken) == null) {
                 logger.LogWarning($"User {dto.UploadedBy} does not exist in the database");
                 return BadRequest();
             }