fix bug in multi_error
fix bug in multi_error

Allardvm/LightGBM,wxchan/LightGBM,huanzhang12/LightGBM,huanzhang12/LightGBM,cbecker/LightGBM,wxchan/LightGBM,wxchan/LightGBM,cbecker/LightGBM,fstonezst/LightGBM,Laurae2/LightGBM,fstonezst/LightGBM,sightmachine/LightGBM,fstonezst/LightGBM,Allardvm/LightGBM,henry0312/LightGBM,olofer/LightGBM,Laurae2/LightGBM,sightmachine/LightGBM,Laurae2/LightGBM,microsoft/LightGBM,henry0312/LightGBM,huanzhang12/lightgbm-gpu,huanzhang12/lightgbm-gpu,sightmachine/LightGBM,Allardvm/LightGBM,cbecker/LightGBM,fstonezst/LightGBM,henry0312/LightGBM,huanzhang12/LightGBM,cbecker/LightGBM,Allardvm/LightGBM,microsoft/LightGBM,Laurae2/LightGBM,wxchan/LightGBM,huanzhang12/LightGBM,microsoft/LightGBM,huanzhang12/lightgbm-gpu,wxchan/LightGBM,olofer/LightGBM,Allardvm/LightGBM,microsoft/LightGBM,huanzhang12/lightgbm-gpu,olofer/LightGBM,olofer/LightGBM,microsoft/LightGBM,fstonezst/LightGBM,henry0312/LightGBM,olofer/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,huanzhang12/LightGBM,sightmachine/LightGBM,huanzhang12/lightgbm-gpu