Fix disconnect during init logging

Summary:
When a client disconnects while it's still initialising, we get a critical error.
But this is expected to happen now and again, so adding a specific error for it, and handling it accordingly.
It doesn't change the control flow, just the logging.

Reviewed By: nikoant

Differential Revision: D32794062

fbshipit-source-id: cf27fb9c345aa6369d338838a46e75a6b7afde41

desktop/flipper-common/src/index.tsx

@@ -34,6 +34,7 @@ export {
   CancelledPromiseError,
   UserUnauthorizedError,
   UserNotSignedInError,
+  NoLongerConnectedToClientError,
   isConnectivityOrAuthError,
   isError,
   isAuthError,

desktop/flipper-common/src/utils/errors.tsx

@@ -60,6 +60,14 @@ export class UserNotSignedInError extends Error {
   name: 'UserNotSignedInError';
 }
 
+export class NoLongerConnectedToClientError extends Error {
+  constructor(msg: string = 'No longer connected to client.') {
+    super(msg);
+    this.name = 'NoLongerConnectedToClientError';
+  }
+  name: 'NoLongerConnectedToClientError';
+}
+
 declare global {
   interface Error {
     interaction?: unknown;

desktop/flipper-ui-core/src/Client.tsx

@@ -15,7 +15,10 @@ import BaseDevice from './devices/BaseDevice';
 import {Logger} from 'flipper-common';
 import {Store} from './reducers/index';
 import {performance} from 'perf_hooks';
-import {reportPluginFailures} from 'flipper-common';
+import {
+  reportPluginFailures,
+  NoLongerConnectedToClientError,
+} from 'flipper-common';
 import {default as isProduction} from './utils/isProduction';
 import {EventEmitter} from 'events';
 import invariant from 'invariant';
@@ -509,7 +512,7 @@ export default class Client extends EventEmitter {
           key: 'appnotconnectedwarning',
           duration: 0.5,
         });
-        reject(new Error('Not connected to client'));
+        reject(new NoLongerConnectedToClientError());
         return;
       }
       if (!fromPlugin || this.isAcceptingMessagesFromPlugin(plugin)) {

desktop/flipper-ui-core/src/dispatcher/flipperServer.tsx

@@ -9,7 +9,11 @@
 
 import React from 'react';
 import {State, Store} from '../reducers/index';
-import {FlipperServer, Logger} from 'flipper-common';
+import {
+  FlipperServer,
+  Logger,
+  NoLongerConnectedToClientError,
+} from 'flipper-common';
 import {FlipperServerImpl} from 'flipper-server-core';
 import {selectClient} from '../reducers/connections';
 import Client from '../Client';
@@ -245,13 +249,24 @@ export async function handleClientConnected(
     type: 'NEW_CLIENT',
     payload: client,
   });
-
+  try {
     await timeout(
       30 * 1000,
       client.init(),
       `[conn] Failed to initialize client ${query.app} on ${query.device_id} in a timely manner`,
     );
-  console.log(`[conn] ${query.app} on ${query.device_id} connected and ready.`);
+    console.log(
+      `[conn] ${query.app} on ${query.device_id} connected and ready.`,
+    );
+  } catch (e) {
+    if (e instanceof NoLongerConnectedToClientError) {
+      console.warn(
+        `[conn] Client ${query.app} on ${query.device_id} disconnected while initialising`,
+      );
+      return;
+    }
+    throw e;
+  }
 }
 
 function getDeviceBySerial(