Refactor ExceptionHandlingMiddleware and update dependencies

Rewrote the `ExceptionHandlingMiddleware` class to improve structure and functionality, changing its namespace to `DigitalData.Core.Exceptions`. Updated the constructor to support a nullable logger and implemented null-conditional logging for unhandled exceptions. Added new package references in `DigitalData.Core.Exceptions.csproj` for `Microsoft.AspNetCore.Http.Abstractions` and `Microsoft.Extensions.Logging.Abstractions`. Introduced a new `DependencyInjection` class to register the middleware in the application's pipeline.

DigitalData.Core.Exceptions/DependencyInjection.cs

@@ -0,0 +1,12 @@
+using Microsoft.AspNetCore.Builder;
+
+namespace DigitalData.Core.Exceptions;
+
+public static class DependencyInjection
+{
+    public static IApplicationBuilder UseExceptionHandlingMiddleware(this IApplicationBuilder app)
+    {
+        app.UseMiddleware<ExceptionHandlingMiddleware>();
+        return app;
+    }
+}

DigitalData.Core.Exceptions/DigitalData.Core.Exceptions.csproj

@@ -6,4 +6,9 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.3.0" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="9.0.5" />
+  </ItemGroup>
+
 </Project>

DigitalData.Core.Exceptions/ExceptionHandlingMiddleware.cs

@@ -0,0 +1,83 @@
+namespace DigitalData.Core.Exceptions;
+
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+using System.Net;
+using System.Text.Json;
+
+/// <summary>
+/// Middleware for handling exceptions globally in the application.
+/// Captures exceptions thrown during the request pipeline execution,
+/// logs them, and returns an appropriate HTTP response with a JSON error message.
+/// </summary>
+public class ExceptionHandlingMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly ILogger<ExceptionHandlingMiddleware>? _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ExceptionHandlingMiddleware"/> class.
+    /// </summary>
+    /// <param name="next">The next middleware in the request pipeline.</param>
+    /// <param name="logger">The logger instance for logging exceptions.</param>
+    public ExceptionHandlingMiddleware(RequestDelegate next, ILogger<ExceptionHandlingMiddleware>? logger = null)
+    {
+        _next = next;
+        _logger = logger;
+    }
+
+    /// <summary>
+    /// Invokes the middleware to handle the HTTP request.
+    /// </summary>
+    /// <param name="context">The HTTP context of the current request.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    public async Task InvokeAsync(HttpContext context)
+    {
+        try
+        {
+            await _next(context); // Continue down the pipeline
+        }
+        catch (Exception ex)
+        {
+            await HandleExceptionAsync(context, ex, _logger);
+        }
+    }
+
+    /// <summary>
+    /// Handles exceptions by logging them and writing an appropriate JSON response.
+    /// </summary>
+    /// <param name="context">The HTTP context of the current request.</param>
+    /// <param name="exception">The exception that occurred.</param>
+    /// <param name="logger">The logger instance for logging the exception.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    private static async Task HandleExceptionAsync(HttpContext context, Exception exception, ILogger? logger = null)
+    {
+        context.Response.ContentType = "application/json";
+
+        string message;
+
+        switch (exception)
+        {
+            case BadRequestException badRequestEx:
+                context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
+                message = badRequestEx.Message;
+                break;
+
+            case NotFoundException notFoundEx:
+                context.Response.StatusCode = (int)HttpStatusCode.NotFound;
+                message = notFoundEx.Message;
+                break;
+
+            default:
+                logger?.LogError(exception, "Unhandled exception occurred.");
+                context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
+                message = "An unexpected error occurred.";
+                break;
+        }
+
+        await context.Response.WriteAsync(JsonSerializer.Serialize(new
+        {
+            message
+        }));
+    }
+}