opening snaphot versions f mc show error of launcher on launching
What I expected to happen was...:
start snapshot 17w06a
What actually happened was...:
snapshot start, but show error if I click on play (image on this report)
Steps to Reproduce:
I don't know, any edit of source code
Environment
windows: 7
java: 8 (I think)
Created Issue:
opening snaphot versions f mc show error of launcher on launching
What I expected to happen was...:
start snapshot 17w06aWhat actually happened was...:
snapshot start, but show error if I click on play (image on this report)Steps to Reproduce:
I don't know, any edit of source codeEnvironment
windows: 7
java: 8 (I think)

So... you edited the source code and this happened?
no, I think that can help, because I can't edit source code of games
You should look up what "reproduce" means.
We need to see your launchers output logs. Please follow the instructions on this page: https://imgur.com/a/N7sQD