Fix issue when deleting script with no evalValue result

src/Evaluator/Evaluator.cpp

@@ -22,6 +22,9 @@ void Evaluator::EvaluateBlockStatement(BoundBlockStatement* statement) {
 }
 
 void Evaluator::EvaluateExpressionStatement(BoundExpressionStatement *statement) {
+    // Delete previously saved value.
+    delete this->_scriptData->_lastValue;
+    // Save new value
     this->_scriptData->_lastValue = this -> EvaluateExpression(statement->GetExpression());
 }