Error downloading launcher files

When I start the launcher and downloaded the files, it tells me the following error:

Client> HELLO FROM WRAPPER
Client> Exception in thread "main" joptsimple.UnrecognizedOptionException: 'username' is not a recognized option
Client> at joptsimple.OptionException.unrecognizedOption(OptionException.java:89)
Client> at joptsimple.OptionParser.handleLongOptionToken(OptionParser.java:445)
Client> at joptsimple.OptionParserState$2.handleArgument(OptionParserState.java:54)
Client> at joptsimple.OptionParser.parse(OptionParser.java:385)
Client> at net.minecraft.launchwrapper.Launch.launch(Launch.java:31)
Client> at net.minecraft.launchwrapper.Launch.main(Launch.java:17)