Fix for block within async when last expression is not an await

Author: MattEdwardsWaggleBee

src/Hyperbee.Expressions/CompilerServices/LoweringVisitor.cs

@@ -181,13 +181,19 @@ protected override Expression VisitBlock( BlockExpression node )
         StateNode firstGoto = null;
         StateNode previousTail = null;
 
-        foreach ( var expression in node.Expressions )
+        for ( var index = 0; index < node.Expressions.Count; index++ )
         {
+            var expression = node.Expressions[index];
+
             if ( RequiresLowering( expression ) )
             {
-                var updated = VisitBranch( expression, joinState, resultVariable ); // Warning: visitation mutates the tail state.
+                var updated =
+                    VisitBranch( expression, joinState, resultVariable ); // Warning: visitation mutates the tail state.
+
+                // handle last expression in the block
+                if ( index == node.Expressions.Count -1 )
+                    previousVariable = updated.Result.Variable;
 
-                previousVariable = updated.Result.Variable;
                 joinState.Result.Variable = previousVariable;
 
                 // Fix tail linked list of Transitions.

src/Hyperbee.Expressions/CompilerServices/StateMachineBuilder.cs

@@ -1,4 +1,4 @@
-using System.Linq.Expressions;
+using System.Linq.Expressions;
 using System.Reflection;
 using System.Reflection.Emit;
 using System.Runtime.CompilerServices;
@@ -53,7 +53,6 @@ public Expression CreateStateMachine( LoweringTransformer loweringTransformer, i
         // 
         // stateMachine.__builder<> = new AsyncInterpreterTaskBuilder<TResult>();
         // stateMachine.__state<> = -1;
-        // stateMachine.<extern_fields> = <extern_fields>;
         //
         // stateMachine.__moveNextDelegate<> = (ref StateMachine stateMachine) => { ... }
         // stateMachine._builder.Start<StateMachineType>( ref stateMachine );

test/Hyperbee.Expressions.Tests/BlockAsyncBasicTests.cs

@@ -627,10 +627,13 @@ public async Task BlockAsync_ShouldAwaitSuccessfully_WithBlockConditional( Compl
             Block(
                 Constant( 5 ),
                 Condition( Constant( true ),
-                    Await( AsyncHelper.Completer(
-                        Constant( completer ),
-                        Constant( 1 )
-                    ) ),
+                    Block(
+                        Await( AsyncHelper.Completer(
+                            Constant( completer ),
+                            Constant( 1 )
+                        ) ),
+                        Constant( 2 )
+                    ),
                     Constant( 0 )
                 )
             )
@@ -642,7 +645,7 @@ public async Task BlockAsync_ShouldAwaitSuccessfully_WithBlockConditional( Compl
         var result = await compiledLambda();
 
         // Assert
-        Assert.AreEqual( 1, result );
+        Assert.AreEqual( 2, result );
     }
 
     public class TestContext