add logging for unhandled errors

Author: wheelsandcogs

src/server.ts

@@ -7,6 +7,19 @@ import { logger } from './utils/logger';
 import { initPassport } from './middleware/passport-auth';
 import { dbManager } from './db/database-manager';
 
+// Without these, an unawaited promise rejection (e.g. an abandoned pg pool acquisition)
+// terminates the process under Node's default --unhandled-rejections=throw, with no log
+// line identifying the offending call site. Log and stay alive for rejections; log and
+// exit for uncaught exceptions since the process state after one is undefined.
+process.on('unhandledRejection', (reason: unknown, promise: Promise<unknown>) => {
+  logger.error({ err: reason, promise }, 'Unhandled promise rejection');
+});
+
+process.on('uncaughtException', (err: Error, origin: string) => {
+  logger.fatal({ err, origin }, 'Uncaught exception, process will exit');
+  setTimeout(() => process.exit(1), 100).unref();
+});
+
 const PORT = config.backend.port;
 
 Promise.resolve()