1 files changed, 10 insertions, 0 deletions
diff --git a/main.go b/main.go
index 26bbce2..6472554 100644
--- a/main.go
+++ b/main.go
@@ -33,6 +33,16 @@ func main() {
 				},
 				Action: func(ctx context.Context, cmd *cli.Command) error {
 					taskIndex := cmd.IntArg("taskIndex")
+
+					// If taskIndex is 0, it's
+					// likely missing; any other
+					// non-positive value is a
+					// deliberate
+					// misconfiguration.
+					if taskIndex <= 0 {
+						return fmt.Errorf("invalid 'do' argument: %d", taskIndex)
+					}
+
 					fmt.Println("completed task: ", taskIndex)
 					return nil
 				},