commands/cli: Fixed Parse required argument check

commands/cli/parse.go

@@ -249,9 +249,11 @@ func parseArgs(inputs []string, stdin *os.File, argDefs []cmds.Argument, recursi
 	}
 
 	// check to make sure we didn't miss any required arguments
-	for _, argDef := range argDefs[argDefIndex:] {
-		if argDef.Required {
-			return nil, nil, fmt.Errorf("Argument '%s' is required", argDef.Name)
+	if len(argDefs) > argDefIndex {
+		for _, argDef := range argDefs[argDefIndex:] {
+			if argDef.Required {
+				return nil, nil, fmt.Errorf("Argument '%s' is required", argDef.Name)
+			}
 		}
 	}