fix: validate -s/--start flag and error on unparseable values (#259)

* fix: validate --start flag input and error on unparseable values

Previously, passing an invalid string to -s/--start (e.g. a typo or
free-form text) would silently fall back to NOW via chrono-node's
parseDate returning null. The command would then proceed as if no start
time was specified.

Now the argParser throws a CommanderError with a clear message when the
input cannot be parsed as a date.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix error message

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Sladuca

src/lib/nodes/utils.ts

@@ -9,7 +9,6 @@ import utc from "dayjs/plugin/utc.js";
 import { parseDurationArgument } from "../../helpers/duration.ts";
 import { logAndQuit } from "../../helpers/errors.ts";
 import { formatNullableDateRange } from "../../helpers/format-time.ts";
-import { parseStartDateOrNow } from "../../helpers/units.ts";
 
 dayjs.extend(utc);
 dayjs.extend(timezone);
@@ -330,11 +329,23 @@ export const maxPriceOption = new Option(
 /**
  * Common --start option using same parser as buy command
  */
+function parseStartDateOrNowOrThrow(val: string): Date | "NOW" {
+  const nowRe = /\b(?:"|')?[nN][oO][wW](?:"|')?\b/;
+  if (nowRe.test(val)) return "NOW";
+  const chronoDate = parseDate(val);
+  if (!chronoDate) {
+    logAndQuit(
+      `Invalid start time: "${val}". Use ISO 8601 format (e.g. '2024-01-15T10:00:00Z'), a relative time (e.g. '+1h'), or 'NOW'.`,
+    );
+  }
+  return chronoDate;
+}
+
 export const startOrNowOption = new Option(
   "-s, --start <start>",
   "Start time (ISO 8601 format:'2022-10-27T14:30:00Z' or relative time like '+1d', or 'NOW')",
 )
-  .argParser(parseStartDateOrNow)
+  .argParser(parseStartDateOrNowOrThrow)
   .default("NOW" as const);
 
 /**