Attach handlers for process errors

Summary:
^
This is an effort to capture and log these errors as to gain visibility when failures occur.

Reviewed By: passy

Differential Revision: D37412861

fbshipit-source-id: 09687a31797aac4c377aa98944ab0701bdf45466

desktop/flipper-server/src/index.tsx

@@ -111,6 +111,9 @@ async function start() {
   if (argv.failFast) {
     flipperServer.on('server-state', ({state}) => {
       if (state === 'error') {
+        console.error(
+          '[flipper-server-process-exit] state changed to error, process will exit.',
+        );
         process.exit(1);
       }
     });
@@ -123,6 +126,23 @@ async function start() {
   await readyForIncomingConnections(flipperServer, companionEnv);
 }
 
+process.on('uncaughtException', (error) => {
+  console.error(
+    '[flipper-server-process-exit] uncaught exception, process will exit.',
+    error,
+  );
+  process.exit(1);
+});
+
+process.on('unhandledRejection', (reason, promise) => {
+  console.warn(
+    '[flipper-server] unhandled rejection for:',
+    promise,
+    'reason:',
+    reason,
+  );
+});
+
 start()
   .then(() => {
     console.log(