Initial support for job queue

ts/jobs/JobError.ts

@@ -0,0 +1,22 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { reallyJsonStringify } from '../util/reallyJsonStringify';
+
+/**
+ * An error that wraps job errors.
+ *
+ * Should not be instantiated directly, except by `JobQueue`.
+ */
+export class JobError extends Error {
+  constructor(public readonly lastErrorThrownByJob: unknown) {
+    super(`Job failed. Last error: ${formatError(lastErrorThrownByJob)}`);
+  }
+}
+
+function formatError(err: unknown): string {
+  if (err instanceof Error) {
+    return err.message;
+  }
+  return reallyJsonStringify(err);
+}