Fix all valgrind leak issues in tests

Signed-off-by: Deukhoofd <deukhoofd@gmail.com>

src/Parser/ParsedStatements/ParsedStatement.hpp

@@ -111,6 +111,10 @@ namespace Porygon::Parser {
             delete _expression;
         }
 
+        void NullifyExpression(){
+            _expression = nullptr;
+        }
+
         const ParsedStatementKind GetKind() const final {
             return ParsedStatementKind::Expression;
         }

src/Parser/Parser.cpp

@@ -525,7 +525,10 @@ namespace Porygon::Parser {
         // If the first item is an expression, and is followed by a comma, we're dealing with a simple {1, 2, 3} kind of array
         if (firstItem->GetKind() == ParsedStatementKind::Expression &&
             (this->Peek()->GetKind() == TokenKind::CommaToken)) {
-            auto expr = ((ParsedExpressionStatement *) firstItem)->GetExpression();
+            auto statement = ((ParsedExpressionStatement *) firstItem);
+            auto expr = statement->GetExpression();
+            statement->NullifyExpression();
+            delete statement;
             auto expressions = vector<const ParsedExpression *>{expr};
             auto n = this->Next(); // consume the comma
             bool hasErrors = false;