app.ts: Fix createApp to log all http server errors

cc @code-asher

src/common/util.ts

@@ -112,3 +112,11 @@ export const getFirstString = (value: string | string[] | object | undefined): s
 
   return typeof value === "string" ? value : undefined
 }
+
+export function logError(prefix: string, err: any): void {
+  if (err instanceof Error) {
+    logger.error(`${prefix}: ${err.message} ${err.stack}`)
+  } else {
+    logger.error(`${prefix}: ${err}`)
+  }
+}

src/node/app.ts

@@ -3,6 +3,7 @@ import express, { Express } from "express"
 import { promises as fs } from "fs"
 import http from "http"
 import * as httpolyglot from "httpolyglot"
+import * as util from "../common/util"
 import { DefaultedArgs } from "./cli"
 import { handleUpgrade } from "./wsRouter"
 
@@ -22,8 +23,21 @@ export const createApp = async (args: DefaultedArgs): Promise<[Express, Express,
       )
     : http.createServer(app)
 
-  await new Promise<http.Server>(async (resolve, reject) => {
-    server.on("error", reject)
+  let resolved = false
+  await new Promise<http.Server>(async (resolve2, reject) => {
+    const resolve = () => {
+      resolved = true
+      resolve2()
+    }
+    server.on("error", (err) => {
+      if (!resolved) {
+        reject(err)
+      } else {
+        // Promise resolved earlier so this is an unrelated error.
+        util.logError("http server error", err)
+      }
+    })
+
     if (args.socket) {
       try {
         await fs.unlink(args.socket)