Process error returned by getPage()

I ran into the following error when trying to run the compiled binary on OpenWRT

$ ./fast-cli
panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
github.com/gesquive/fast-cli/fast.getFastToken(0x467810, 0x3)
        /home/mbukowski/go/src/github.com/gesquive/fast-cli/fast/fast-api.go:62 +0x408
github.com/gesquive/fast-cli/fast.GetDlUrls(0x0, 0x3, 0x32e528, 0xc74380, 0xc64e6c)
        /home/mbukowski/go/src/github.com/gesquive/fast-cli/fast/fast-api.go:15 +0x38
main.run(0x61a5e0, 0xc0c6e0, 0x0, 0x1)
        /home/mbukowski/go/src/github.com/gesquive/fast-cli/main.go:84 +0x64
github.com/spf13/cobra.(*Command).execute(0x61a5e0, 0xc0a038, 0x1, 0x1, 0x61a5e0, 0xc0a038)
        /home/mbukowski/go/src/github.com/spf13/cobra/command.go:854 +0x234
github.com/spf13/cobra.(*Command).ExecuteC(0x61a5e0, 0x25, 0xc64f80, 0x2)
        /home/mbukowski/go/src/github.com/spf13/cobra/command.go:958 +0x2d4
github.com/spf13/cobra.(*Command).Execute(...)
        /home/mbukowski/go/src/github.com/spf13/cobra/command.go:895
main.Execute(0xc10370, 0x10)
        /home/mbukowski/go/src/github.com/gesquive/fast-cli/main.go:47 +0x144
main.main()
        /home/mbukowski/go/src/github.com/gesquive/fast-cli/main.go:38 +0x11c

This happened both with fast-cli and fast-cli -n. Processing the error returned by getPage() I did get

$ ./fast-cli
Get "https://fast.com": x509: certificate signed by unknown authority

and identified that the CA certificates are missing. After installing ca-bundle on OpenWRT (opkg install ca-bundle) the error was resolved.