Fix CLI bug with start-time being blank

x/incentives/client/cli/tx.go

@@ -59,7 +59,7 @@ func NewCreateGaugeCmd() *cobra.Command {
 				return err
 			}
 			if timeStr == "" { // empty start time
-				// do nothing
+				startTime = time.Unix(0, 0)
 			} else if timeUnix, err := strconv.ParseInt(timeStr, 10, 64); err == nil { // unix time
 				startTime = time.Unix(timeUnix, 0)
 			} else if timeRFC, err := time.Parse(time.RFC3339, timeStr); err == nil { // RFC time