Revert to 35314725, a version that works

.github/workflows/publish-docker.yml

+name: Publish Docker
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  publish-docker:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: docker/build-push-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+          repository: excalidraw/excalidraw-room
+          tag_with_ref: true
+          tag_with_sha: true

Dockerfile

+FROM node:12-alpine
+
+WORKDIR /excalidraw-room
+
+COPY package.json yarn.lock ./
+RUN yarn
+
+COPY tsconfig.json ./
+COPY src ./src
+RUN yarn build
+
+EXPOSE 80
+CMD ["yarn", "start"]

package.json

     "build": "tsc",
     "fix": "yarn prettier --write",
     "lint": "yarn prettier --list-different",
-    "postinstall": "npm run build",
     "prettier": "prettier \"**/*.{ts,md,json,yaml,yml}\"",
     "start": "node dist/index.js",
     "test": "yarn lint"
   "dependencies": {
     "debug": "4.1.1",
     "eslint": "7.3.1",
-    "eslint-config-prettier": "6.11.0",
+    "eslint-config-prettier": "6.10.1",
     "eslint-plugin-prettier": "3.1.4",
     "express": "4.17.1",
     "prettier": "2.0.5",
     "socket.io": "2.3.0"
   },
   "devDependencies": {
-    "@types/socket.io": "2.1.11",
+    "@types/socket.io": "2.1.4",
     "@types/debug": "4.1.5",
-    "@types/express": "4.17.7",
+    "@types/express": "4.17.6",
     "@types/node": "13.9.8",
-    "typescript": "4.0.2"
+    "typescript": "3.9.5"
   },
   "eslintConfig": {
     "extends": [

yarn.lock

   resolved "https://registry.yarnpkg.com/@types/debug/-/debug-4.1.5.tgz#b14efa8852b7768d898906613c23f688713e02cd"
   integrity sha512-Q1y515GcOdTHgagaVFhHnIFQ38ygs/kmxdNpvpou+raI9UO3YZcHDngBSYKQklcKlvA7iuQlmIKbzvmxcOE9CQ==
 
-"@types/engine.io@*":
-  version "3.1.4"
-  resolved "https://registry.yarnpkg.com/@types/engine.io/-/engine.io-3.1.4.tgz#3d9472711d179daa7c95c051e50ad411e18a9bdc"
-  integrity sha512-98rXVukLD6/ozrQ2O80NAlWDGA4INg+tqsEReWJldqyi2fulC9V7Use/n28SWgROXKm6003ycWV4gZHoF8GA6w==
-  dependencies:
-    "@types/node" "*"
-
 "@types/express-serve-static-core@*":
   version "4.17.2"
   resolved "https://registry.yarnpkg.com/@types/express-serve-static-core/-/express-serve-static-core-4.17.2.tgz#f6f41fa35d42e79dbf6610eccbb2637e6008a0cf"
     "@types/node" "*"
     "@types/range-parser" "*"
 
-"@types/express@4.17.7":
-  version "4.17.7"
-  resolved "https://registry.yarnpkg.com/@types/express/-/express-4.17.7.tgz#42045be6475636d9801369cd4418ef65cdb0dd59"
-  integrity sha512-dCOT5lcmV/uC2J9k0rPafATeeyz+99xTt54ReX11/LObZgfzJqZNcW27zGhYyX+9iSEGXGt5qLPwRSvBZcLvtQ==
+"@types/express@4.17.6":
+  version "4.17.6"
+  resolved "https://registry.yarnpkg.com/@types/express/-/express-4.17.6.tgz#6bce49e49570507b86ea1b07b806f04697fac45e"
+  integrity sha512-n/mr9tZI83kd4azlPG5y997C/M4DNABK9yErhFM6hKdym4kkmd9j0vtsJyjFIwfRBxtrxZtAfGZCNRIBMFLK5w==
   dependencies:
     "@types/body-parser" "*"
     "@types/express-serve-static-core" "*"
     "@types/express-serve-static-core" "*"
     "@types/mime" "*"
 
-"@types/socket.io@2.1.11":
-  version "2.1.11"
-  resolved "https://registry.yarnpkg.com/@types/socket.io/-/socket.io-2.1.11.tgz#e0d6759880e5f9818d5297a3328b36641bae996b"
-  integrity sha512-bVprmqPhJMLb9ZCm8g0Xy8kwBFRbnanOWSxzWkDkkIwxTvud5tKMfAJymXX6LQbizUKCS1yima7JM4BeLqjNqA==
+"@types/socket.io@2.1.4":
+  version "2.1.4"
+  resolved "https://registry.yarnpkg.com/@types/socket.io/-/socket.io-2.1.4.tgz#674e7bc193c5ccdadd4433f79f3660d31759e9ac"
+  integrity sha512-cI98INy7tYnweTsUlp8ocveVdAxENUThO0JsLSCs51cjOP2yV5Mqo5QszMDPckyRRA+PO6+wBgKvGvHUCc23TQ==
   dependencies:
-    "@types/engine.io" "*"
     "@types/node" "*"
 
 accepts@~1.3.4, accepts@~1.3.7:
   resolved "https://registry.yarnpkg.com/escape-string-regexp/-/escape-string-regexp-1.0.5.tgz#1b61c0562190a8dff6ae3bb2cf0200ca130b86d4"
   integrity sha1-G2HAViGQqN/2rjuyzwIAyhMLhtQ=
 
-eslint-config-prettier@6.11.0:
-  version "6.11.0"
-  resolved "https://registry.yarnpkg.com/eslint-config-prettier/-/eslint-config-prettier-6.11.0.tgz#f6d2238c1290d01c859a8b5c1f7d352a0b0da8b1"
-  integrity sha512-oB8cpLWSAjOVFEJhhyMZh6NOEOtBVziaqdDQ86+qhDHFbZXoRTM7pNSvFRfW/W/L/LrQ38C99J5CGuRBBzBsdA==
+eslint-config-prettier@6.10.1:
+  version "6.10.1"
+  resolved "https://registry.yarnpkg.com/eslint-config-prettier/-/eslint-config-prettier-6.10.1.tgz#129ef9ec575d5ddc0e269667bf09defcd898642a"
+  integrity sha512-svTy6zh1ecQojvpbJSgH3aei/Rt7C6i090l5f2WQ4aB05lYHeZIR1qL4wZyyILTbtmnbHP5Yn8MrsOJMGa8RkQ==
   dependencies:
     get-stdin "^6.0.0"
 
     type-check "~0.4.0"
 
 lodash@^4.17.14:
-  version "4.17.20"
-  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.20.tgz#b44a9b6297bcb698f1c51a3545a2b3b368d59c52"
-  integrity sha512-PlhdFcillOINfeV7Ni6oF1TAEayyZBoZ8bcshTHqOYJYlrqzRK5hagpagky5o4HfCzzd1TRkXPMFq6cKk9rGmA==
+  version "4.17.15"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"
+  integrity sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==
 
 media-typer@0.3.0:
   version "0.3.0"
     media-typer "0.3.0"
     mime-types "~2.1.24"
 
-typescript@4.0.2:
-  version "4.0.2"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.0.2.tgz#7ea7c88777c723c681e33bf7988be5d008d05ac2"
-  integrity sha512-e4ERvRV2wb+rRZ/IQeb3jm2VxBsirQLpQhdxplZ2MEzGvDkkMmPglecnNDfSUBivMjP93vRbngYYDQqQ/78bcQ==
+typescript@3.9.5:
+  version "3.9.5"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.9.5.tgz#586f0dba300cde8be52dd1ac4f7e1009c1b13f36"
+  integrity sha512-hSAifV3k+i6lEoCJ2k6R2Z/rp/H3+8sdmcn5NrS3/3kE7+RyZXm9aqvxWqjEXHAd8b0pShatpcdMTvEdvAJltQ==
 
 unpipe@1.0.0, unpipe@~1.0.0:
   version "1.0.0"