Terminal print "ReferenceError: self is not defined "

[DarkFlame-xc]

Hello technical guru , I am a programming enthusiast from China , what’s more , I think the project is so goods,but I want to know how to resolve the problem that the Terminal print "ReferenceError: self is not defined " when I run the command "npm run test" , my English is not very well , I want someone to help me with this promble , Thanks