fix crash due to bad cast
fix crash due to bad cast

peertracksinc/muse,peertracksinc/muse,bigoc/openchain,pmconrad/graphene,pmconrad/graphene,pmconrad/graphene,oxarbitrage/bitshares-core,bigoc/openchain,abitmore/bitshares-2,abitmore/bitshares-2,cryptonomex/graphene,oxarbitrage/bitshares-core,bigoc/openchain,bitshares/bitshares-2,peertracksinc/muse,abitmore/bitshares-2,bitsuperlab/cpp-play2,pmconrad/graphene,bigoc/openchain,bitsuperlab/cpp-play2,bitshares/bitshares-2,oxarbitrage/bitshares-core,cryptonomex/graphene,peertracksinc/muse,bitsuperlab/cpp-play2,bitshares/bitshares-2,oxarbitrage/bitshares-core,cryptonomex/graphene,abitmore/bitshares-2,bitshares/bitshares-2