--- a/web/src/format.ts	2026-03-02 09:14:03.000000000 +0000
+++ b/web/src/format.ts	2026-03-02 10:41:55.000000000 +0000
@@ -3,0 +4 @@
+  locale?: string;
@@ -6,0 +8 @@
+const DEFAULT_LOCALE = "en-GB";
@@ -36 +38,5 @@
-  return Number.parseInt(cleaned, 10);
+  const parsed = Number.parseInt(cleaned, 10);
+  if (Number.isNaN(parsed)) {
+    throw new RangeError("parseMinor: no digits in " + JSON.stringify(text));
+  }
+  return parsed;