added exception handling

api/Controllers/PersonController.cs

@@ -1,19 +1,15 @@
 using Microsoft.AspNetCore.Mvc;
 using api.Services;
 using api.DTOs;
+using Microsoft.EntityFrameworkCore;
 
 namespace api.Controllers
 {
     [ApiController]
     [Route("api/[controller]")]
-    public class PersonController : ControllerBase
+    public class PersonController(IPersonService personService) : ControllerBase
     {
-        private readonly IPersonService _personService;
-
-        public PersonController(IPersonService personService)
-        {
-            _personService = personService;
-        }
+        private readonly IPersonService _personService = personService;
 
         [HttpGet]
         public async Task<IActionResult> GetAll()
@@ -39,8 +35,20 @@ namespace api.Controllers
         [HttpPost]
         public async Task<IActionResult> Add(PersonDto personDto)
         {
+            try
+            {
             await _personService.AddPersonAsync(personDto);
             return CreatedAtAction(nameof(GetByUsername), new { username = personDto.Username }, personDto);
+                
+            }
+            catch (ArgumentException ex)
+            {
+                return BadRequest(ex.Message);
+            }
+            catch (DbUpdateException)
+            {
+                return Conflict("Username already exists");
+            }
         }
 
         [HttpPut("username/{username}")]