Fix NullReferenceException during warmup in live mode
Fix NullReferenceException during warmup in live mode

jameschch/Lean,jameschch/Lean,JKarathiya/Lean,StefanoRaggi/Lean,jameschch/Lean,QuantConnect/Lean,JKarathiya/Lean,StefanoRaggi/Lean,QuantConnect/Lean,StefanoRaggi/Lean,JKarathiya/Lean,StefanoRaggi/Lean,AlexCatarino/Lean,QuantConnect/Lean,AlexCatarino/Lean,AlexCatarino/Lean,QuantConnect/Lean,StefanoRaggi/Lean,JKarathiya/Lean,AlexCatarino/Lean,jameschch/Lean,jameschch/Lean