My login function look like below:-

    [Function("Loginxyz")]
    public async Task<IActionResult> GenerateToken(
        [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "user/login")] HttpRequestData req,
        ILogger log)
    {
        try
        {

            if (requestData.BarCode != null)
            {
                var localLoginRequest = JsonConvert.DeserializeObject<xyz>(requestBody);
                token = await _tokenService.GenerateToken(localLoginRequest);
            }

            if (token == null)
                return new UnauthorizedResult();

            return new OkObjectResult(new { access_token = token });
        }
        catch (AggregateException ae)
        {
            // Handle multiple exceptions
            foreach (var innerException in ae.InnerExceptions)
            {
                log.LogError(innerException, "An error occurred");
                // Handle the inner exception based on its type
            }

            // Return a specific error response based on the aggregate exception
            return new BadRequestObjectResult("An error occurred");
        }
        catch (AuthenticationServiceException ex)
        {
            // Log the error with detailed message
            log.LogError($"Error during token generation: {ex.Message}", ex);

            // Create a custom error response object
            var errorResponse = new
            {
                Error = ex.Message,
                StatusCode = StatusCodes.Status400BadRequest
            };

            // Return the error response with the appropriate status code
            return new JsonResult(errorResponse) { StatusCode = StatusCodes.Status400BadRequest };

        }
        catch (LoginConflictException ex)
        {
            // Log the error with detailed message
            log.LogError($"Error during token generation: {ex.Message}", ex);

            // Create a custom error response object
            var errorResponse = new
            {
                Error = ex.Message,
                StatusCode = StatusCodes.Status409Conflict
            };

            // Return the error response with the appropriate status code
            return new JsonResult(errorResponse) { StatusCode = StatusCodes.Status409Conflict };

        }
        catch (Exception ex)
        {
            log.LogError($"Error during token generation: {ex.Message}");
            return new StatusCodeResult(StatusCodes.Status500InternalServerError);
        }
    }

My service class look like:-

        public async Task<TokenResponseDto> GenerateToken(object tokenRequest)
    {
        try
        {

                return await tokenGenerator.GenerateToken(tokenRequest);
        }
        catch (Exception ex)
        {
            throw; // Rethrow the exception
        }
    }

I throw an error in the tokenGenerator.GenerateToken method and rethrow it in my service class. My expectation is that when I rethrow the error in the service class, it should be caught in my Azure Function.

However, the error I’m receiving from the rethrow is:

“An exception was thrown by the invocation.
Exception: System.ArgumentNullException: Value cannot be null. (Parameter ‘logger’)”

This is confusing because I was throwing a custom error, not related to ArgumentNullException.

can someone help me on this to understand?