fix error with sending responses

BookHive/Endpoints/Loans/CreateLoanEndpoint.cs

@@ -52,6 +52,6 @@ public class CreateLoanEndpoint(LoanRepository loanRepository, BookRepository bo
         }
 
         await loanRepository.AddAsync(mapper.Map<Loan>(req), ct);
-        await Send.OkAsync(cancellation: ct);
+        await Send.NoContentAsync(ct);
     }
 }

BookHive/Endpoints/Loans/PatchReturnLoanEndpoint.cs

@@ -25,11 +25,11 @@ public class PatchReturnLoanEndpoint(LoanRepository loanRepository) : Endpoint<P
         if (loan is null)
         {
             await Send.NotFoundAsync(ct);
-            await Send.OkAsync(cancellation: ct);
+            return;
         }
         
         loan?.ReturnDate = req.ReturnDate;
         await loanRepository.SaveChangesAsync(ct);
-        await Send.OkAsync(cancellation: ct);
+        await Send.NoContentAsync(ct);
     }
 }