fix: don't crash parseDate when dateFormat contains timezone tokens

src/date_utils.ts

@@ -306,11 +306,20 @@ export function parseDate(
   const formats = Array.isArray(dateFormat) ? dateFormat : [dateFormat];
 
   for (const format of formats) {
-    const parsedDate = parse(value, format, refDate, {
-      locale: localeObject,
-      useAdditionalWeekYearTokens: true,
-      useAdditionalDayOfYearTokens: true,
-    });
+    // date-fns `parse` throws a RangeError for format tokens it cannot
+    // consume (e.g. the `z`/`zzz` timezone tokens, which are format-only).
+    // Guard against that so an unparseable token in `dateFormat` does not
+    // crash callers such as handleChange and discard the user's input.
+    let parsedDate: Date;
+    try {
+      parsedDate = parse(value, format, refDate, {
+        locale: localeObject,
+        useAdditionalWeekYearTokens: true,
+        useAdditionalDayOfYearTokens: true,
+      });
+    } catch {
+      continue;
+    }
     if (
       isValid(parsedDate) &&
       (!strictParsing || value === formatDate(parsedDate, format, locale))

src/test/date_utils_test.test.ts

@@ -1121,6 +1121,24 @@ describe("date_utils", () => {
       expect(actual).toEqual(expected);
     });
 
+    it("should not throw when dateFormat contains an unparseable timezone token (#6303)", () => {
+      // date-fns `parse` cannot consume the `z`/`zzz` timezone tokens and
+      // throws a RangeError ("Format string contains an unescaped latin
+      // alphabet character `z`"). parseDate must swallow that so typing an
+      // input does not crash handleChange and the user's value is not lost.
+      const value = "July 6, 2026 3:30 PM (GMT+0)";
+      const dateFormat = "MMMM d, yyyy h:mm aa (zzz)";
+
+      let actual: Date | null = null;
+      expect(() => {
+        actual = parseDate(value, dateFormat, undefined, false);
+      }).not.toThrow();
+
+      // The date/time portion still resolves via the native Date fallback.
+      expect(actual).not.toBeNull();
+      expect(actual).toEqual(new Date(2026, 6, 6, 15, 30, 0, 0));
+    });
+
     describe("native Date fallback when strictParsing is false (#6164)", () => {
       it("should parse date in different format using native Date fallback", () => {
         // User types MM/dd/yyyy but dateFormat is yyyy-MM-dd