Panic on run without command

[handlename]

$ aswrap ssmwrap -paths /dev05
panic: runtime error: index out of range

goroutine 1 [running]:
github.com/handlename/ssmwrap.runCommand(0xc0000880b0, 0x0, 0x0, 0xc0000fc000, 0x50, 0x50, 0x0, 0x0)
	/Users/nagata-hiroaki/src/github.com/handlename/ssmwrap/app.go:53 +0xf5
github.com/handlename/ssmwrap.Run(0xc0000871b0, 0x1, 0x1, 0x0, 0xc0000880b0, 0x0, 0x0, 0x14388c0, 0x1680080, 0xc0000871d0, ...)
	/Users/nagata-hiroaki/src/github.com/handlename/ssmwrap/app.go:45 +0x16c
main.main()
	/Users/nagata-hiroaki/src/github.com/handlename/ssmwrap/cmd/ssmwrap/main.go:206 +0x48e