Fix C# generation

```
[OK] G0_HelloWorld (mcs test/w/G0_HelloWorld.cs)
[OK] G1_Function (mcs test/w/G1_Function.cs)
[OK] G1_Grouping (mcs test/w/G1_Grouping.cs)
[OK] G1_If (mcs test/w/G1_If.cs)
[OK] G1_Let (mcs test/w/G1_Let.cs)
[OK] G1_Operator (mcs test/w/G1_Operator.cs)
[OK] G1_StringInterpolation (mcs test/w/G1_StringInterpolation.cs)
[OK] G1_Var (mcs test/w/G1_Var.cs)
[OK] G1_While (mcs test/w/G1_While.cs)
[OK] G1_WhileBreak (mcs test/w/G1_WhileBreak.cs)
[OK] G2_Asm (mcs test/w/G2_Asm.cs)
[OK] G2_CrossReferenceFunction (mcs test/w/G2_CrossReferenceFunction.cs)
[OK] G2_FunctionNoReturn (mcs test/w/G2_FunctionNoReturn.cs)
[OK] G2_FunctionParameter (mcs test/w/G2_FunctionParameter.cs)
[OK] G2_LetInFunction (mcs test/w/G2_LetInFunction.cs)
[OK] G2_Precedence (mcs test/w/G2_Precedence.cs)
[OK] G3_Boolean (mcs test/w/G3_Boolean.cs)
[OK] G3_Float (mcs test/w/G3_Float.cs)
[OK] G3_Int (mcs test/w/G3_Int.cs)
[OK] G3_IntArray (mcs test/w/G3_IntArray.cs)
[OK] G3_IntMap (mcs test/w/G3_IntMap.cs)
[OK] G3_Null (mcs test/w/G3_Null.cs)
[OK] G3_String (mcs test/w/G3_String.cs)
[OK] G3_StringConcat (mcs test/w/G3_StringConcat.cs)
[OK] G3_StringInterpolation (mcs test/w/G3_StringInterpolation.cs)
[OK] G4_KeyNotFound (mcs test/w/G4_KeyNotFound.cs)
[OK] G4_OutOfIndex (mcs test/w/G4_OutOfIndex.cs)
[OK] G4_SyntaxError (mcs test/w/G4_SyntaxError.cs)
[OK] G4_Throw (mcs test/w/G4_Throw.cs)
[OK] G4_Try (mcs test/w/G4_Try.cs)
[OK] G4_ZeroDivision (mcs test/w/G4_ZeroDivision.cs)
[OK] G5_ApplyFunction (mcs test/w/G5_ApplyFunction.cs)
[OK] G5_LetFunction (mcs test/w/G5_LetFunction.cs)
[OK] G5_VarFunction (mcs test/w/G5_VarFunction.cs)
[OK] G6_Class (mcs test/w/G6_Class.cs)
[OK] G6_Constructor (mcs test/w/G6_Constructor.cs)
[OK] G6_DynamicBinding (mcs test/w/G6_DynamicBinding.cs)
[OK] G6_InstanceOf (mcs test/w/G6_InstanceOf.cs)
[OK] G6_SubClass (mcs test/w/G6_SubClass.cs)
[OK] G7_InferFunction (mcs test/w/G7_InferFunction.cs)
[OK] G8_Continue (mcs test/w/G8_Continue.cs)
[OK] G8_Math (mcs test/w/G8_Math.cs)
[OK] G8_RequireSyntax (mcs test/w/G8_RequireSyntax.cs)
[FAILED] G9_BinaryTrees (mcs test/w/G9_BinaryTrees.cs)
[OK] G9_Fibonacci (mcs test/w/G9_Fibonacci.cs)
[OK] G9_MathSqrt (mcs test/w/G9_MathSqrt.cs)
[OK] Gx_Utf8String (mcs test/w/Gx_Utf8String.cs)
# of OK: 47, # of FAILED: 1
```