fix: handle empty credentials when listing credentials (#799)

internal/cmd/configure/list.go

@@ -1,6 +1,8 @@
 package configure
 
 import (
+	"fmt"
+
 	"github.com/saucelabs/saucectl/internal/credentials"
 	"github.com/spf13/cobra"
 )
@@ -14,6 +16,10 @@ func ListCommand() *cobra.Command {
 		Short: "Shows the current credentials and their origin.",
 		Run: func(cmd *cobra.Command, args []string) {
 			creds := credentials.Get()
+			if creds.Username == "" || creds.AccessKey == "" {
+				fmt.Println(`Credentials have not been set. Please use "saucectl configure" to set your credentials.`)
+				return
+			}
 			printCreds(creds)
 		},
 	}