Bug: SIGSEGV when describing a DDB table

[deigote]

$ awstools ddb desc -t some-table-of-mine
some-table-of-mine
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x2109a9]

goroutine 1 [running]:
panic(0x6dbda0, 0xc420014080)
	/home/travis/.gimme/versions/go1.7.3.linux.amd64/src/runtime/panic.go:500 +0x1a1
github.com/sam701/awstools/ddb.DescribeTable(0xc420095180, 0x0, 0xc420095180)
	/home/travis/gopath/src/github.com/sam701/awstools/ddb/describe_table.go:48 +0x479
github.com/sam701/awstools/vendor/github.com/urfave/cli.HandleAction(0x666f00, 0x8239a0, 0xc420095180, 0xc42006ea00, 0x0)
	/home/travis/gopath/src/github.com/sam701/awstools/vendor/github.com/urfave/cli/app.go:485 +0xd4
github.com/sam701/awstools/vendor/github.com/urfave/cli.Command.Run(0x7d3a05, 0x8, 0x7d1ddc, 0x4, 0x0, 0x0, 0x0, 0x7d7647, 0xe, 0x0, ...)
	/home/travis/gopath/src/github.com/sam701/awstools/vendor/github.com/urfave/cli/command.go:193 +0xb96
github.com/sam701/awstools/vendor/github.com/urfave/cli.(*App).RunAsSubcommand(0xc42015e680, 0xc420094f00, 0x0, 0x0)
	/home/travis/gopath/src/github.com/sam701/awstools/vendor/github.com/urfave/cli/app.go:374 +0xb1a
github.com/sam701/awstools/vendor/github.com/urfave/cli.Command.startApp(0x7d3a15, 0x8, 0x7d1882, 0x3, 0x0, 0x0, 0x0, 0x7d9f3f, 0x11, 0x0, ...)
	/home/travis/gopath/src/github.com/sam701/awstools/vendor/github.com/urfave/cli/command.go:280 +0x82c
github.com/sam701/awstools/vendor/github.com/urfave/cli.Command.Run(0x7d3a15, 0x8, 0x7d1882, 0x3, 0x0, 0x0, 0x0, 0x7d9f3f, 0x11, 0x0, ...)
	/home/travis/gopath/src/github.com/sam701/awstools/vendor/github.com/urfave/cli/command.go:79 +0x16a5
github.com/sam701/awstools/vendor/github.com/urfave/cli.(*App).Run(0xc42015e340, 0xc42000a140, 0x5, 0x5, 0x0, 0x0)
	/home/travis/gopath/src/github.com/sam701/awstools/vendor/github.com/urfave/cli/app.go:250 +0x812
main.main()
	/home/travis/gopath/src/github.com/sam701/awstools/main.go:242 +0x1890