Used car purchase Astra engine goes off-

Hello I intend to buy an Opel Astra Caravan 1.6 for my daughter. Is EZ 10/2005, about 60,000 km. The car has a problem, according to the seller the engine goes off as soon as it is warm, so after about 10 minutes. After a short time he should get started again, but then again and again go out. Have looked at the car so far only briefly. In cold condition it starts, runs calmly and has no problems. I then did the thing with gas and brake and in the day kil meter counters were displayed 12 errors, I could not remember all of them now. But were among other things 20100 to 20400 (o.ä) errors were probably searched but not found. The car has an additional LPG system and is due to the defect clearly cheaper than an equivalent model that is ok. The car also goes out in petrol operation, so has nothing specifically to do with the gas system. My question is whether you should buy the car and what the most expensive assuming e damage would be.