fix: improve exception handling with ExceptionDispatchInfo

- Updated PipelineBuilder and QueryProcessor to use `ExceptionDispatchInfo.Capture` for correct stack trace preservation.
- Added compiler-required `throw` statements to unreachable code paths.

Author: holytshirt

src/Paramore.Darker/PipelineBuilder.cs

@@ -8,6 +8,7 @@
 using Paramore.Darker.Attributes;
 using Paramore.Darker.Exceptions;
 using Paramore.Darker.Logging;
+using System.Runtime.ExceptionServices;   // ✨ new
 
 namespace Paramore.Darker
 {
@@ -53,10 +54,10 @@ public Func<IQuery<TResult>, TResult> Build(IQuery<TResult> query, IQueryContext
                         {
                             return (TResult)executeMethodInfo.Invoke(_handler, new object[] { r });
                         }
-                        catch (TargetInvocationException targetInvocationException)
+                        catch (TargetInvocationException ex) when (ex.InnerException != null) 
                         {
-                            // Unwrap the original exception instead of wrapping it in a FormatException
-                            throw targetInvocationException.InnerException;
+                            ExceptionDispatchInfo.Capture(ex.InnerException).Throw();
+                            throw; // never reached
                         }
                     }
             };
@@ -97,10 +98,10 @@ public Func<IQuery<TResult>, CancellationToken, Task<TResult>> BuildAsync(IQuery
                     {
                         return (Task<TResult>)executeAsyncMethodInfo.Invoke(_handler, new object[] { r, ct });
                     }
-                    catch (TargetInvocationException targetInvocationException)
+                    catch (TargetInvocationException ex) when (ex.InnerException != null)
                     {
-                        // Unwrap the original exception instead of wrapping it in a FormatException
-                        throw targetInvocationException.InnerException;
+                        ExceptionDispatchInfo.Capture(ex.InnerException).Throw();
+                        throw; // never reached for complier 
                     }
                 }
             };

src/Paramore.Darker/QueryProcessor.cs

@@ -6,6 +6,7 @@
 using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 using Paramore.Darker.Logging;
+using System.Runtime.ExceptionServices;
 
 namespace Paramore.Darker
 {
@@ -46,9 +47,10 @@ public TResult Execute<TResult>(IQuery<TResult> query)
                 {
                     return entryPoint.Invoke(query);
                 }
-                catch (TargetInvocationException targetInvocationException)
+                catch (TargetInvocationException ex) when (ex.InnerException != null)
                 {
-                    throw targetInvocationException.InnerException;
+                    ExceptionDispatchInfo.Capture(ex.InnerException).Throw();
+                    throw; // never reached, but required by compiler
                 }
                 catch (Exception ex)
                 {
@@ -70,9 +72,10 @@ public TResult Execute<TResult>(IQuery<TResult> query)
                     _logger.LogDebug("Invoking async pipeline...");
                     return await entryPoint.Invoke(query, cancellationToken).ConfigureAwait(false);
                 }
-                catch (TargetInvocationException targetInvocationException)
+                catch (TargetInvocationException ex) when (ex.InnerException != null)
                 {
-                    throw targetInvocationException.InnerException;
+                    ExceptionDispatchInfo.Capture(ex.InnerException).Throw();
+                    throw; // never reached, but required by compiler
                 }
                 catch (Exception ex)
                 {