diff --git a/scripts/lib/error-format.d.mts b/scripts/lib/error-format.d.mts
new file mode 100644
index 000000000000..123b21fab37c
--- /dev/null
+++ b/scripts/lib/error-format.d.mts
@@ -0,0 +1,2 @@
+/** Return a readable message for Error and non-Error thrown values. */
+export function formatErrorMessage(error: unknown): string;