pure virtual method called terminate called without an active exception - c++

Question

I have an issue. I am making a game where i check if a projectile is below the screen, if true i want to delete that object. My problem is that when the projectile actually goes below sceen my game crashes with the error:
pure virtual method called terminate called without an active
exception
which i think is very wierd because my projectile class has nothing to do with a virtual method or abstract class. This is the update methods:
void GameScene::updateLogic() {
if (projectile) {
if (projectile -> position().y > 1200) {
t1Turn = true;
delete projectile;
}
else {
projectile->update();
}
}
}
void GameScene::draw() {
if (projectile) {
projectile->draw(_window);
}
}
The projectile pointer is set to nullptr in the constructor of the gamescene:
_p = nullptr;
The projectile class:
Projectile::Projectile(sf::Vector2f spawnPoint, sf::Vector2f initVel, Tank* target, bool& turn) : _spawnPoint(spawnPoint), _initVel(initVel), _target(target), _turn(turn) {}
Projectile::~Projectile(){}
void Projectile::update(){
if (_collisionBox.intersects(_target->getBox())) {
_target->removeHealth(20);
}
_elapsed = clock.getElapsedTime().asSeconds();
_time += _elapsed;
clock.restart();
dx = (_initVel.x * _time);
dy = (_initVel.y * _time + (1900*pow(_time, 2) / 2));
_position = sf::Vector2f(_spawnPoint.x+dx, _spawnPoint.y+dy);
_collisionBox = _projectileSprite.getGlobalBounds();
}
void Projectile::draw(sf::RenderWindow &window) {
_projectileSprite.setPosition(_position);
window.draw(_projectileSprite);
}
sf::Vector2f Projectile::position () {
return _position;
}
The projectile inherits from a sprite class but thats about it:
class Projectile : Sprites {
It has no association with a pure virtual method...
EDIT: When running the debugger it breaks at:
void Projectile::draw(sf::RenderWindow &window) { window <incomplete type>
_projectileSprite.setPosition(_position);
window.draw(_projectileSprite); <--------------------
}
But how can window be of incomplete type? What has that to do with a virtual method which the original error message say?