[Konstantinos]

pawn Code:

for(new i = 0; i < sizeof(FamilyInfo); i++)
{
    for(new d = 0 ; d < MAX_GANG_VEHICLES; d++)
    {
        if(FamilyVehicleInfo[i][d][fvLocked] != 0 && FamilyVehicleInfo[i][d][fvLock] > 0)
        {
            LockGangVehicle(i, FamilyVehicleInfo[i][d][fvId], FamilyVehicleInfo[i][d][fvLock]);
        }
    }
}

FamilyVehicleInfo[i][d][fvId] is INVALID_VEHICLE_ID. You could check if it's not before calling LockGangVehicle:

pawn Code:

if(FamilyVehicleInfo[i][d][fvLocked] != 0 && FamilyVehicleInfo[i][d][fvLock] > 0 && FamilyVehicleInfo[i][d][fvId] != INVALID_VEHICLE_ID)

or in case the reset value is changed to be more accurate:

pawn Code:

if(FamilyVehicleInfo[i][d][fvLocked] != 0 && FamilyVehicleInfo[i][d][fvLock] > 0 && 1 <= FamilyVehicleInfo[i][d][fvId] <= 1999)

That will prevent the run time error from OnPlayerSpawn but if LockGangVehicle is called elsewhere and carid is still a valid, you'll need to modify that function as well.