Fix skill fail packet handling causing nullptr crash when switching characters
How to reproduce: spam emote then quickly switch char
Thread 1 "manaplus" received signal SIGSEGV, Segmentation fault. SkillDialog::getSkill (this=0x0, id=id@entry=1) at gui/windows/skilldialog.cpp:805
0 SkillDialog::getSkill (this=0x0, id=id@entry=1) at gui/windows/skilldialog.cpp:805 1 EAthena::SkillRecv::processSkillFailed (msg=...) at net/eathena/skillrecv.cpp:302 ...