fix(snap): installation issue

"The SUID sandbox helper binary was found, but is not configured correctly."
electron/electron#17972

package.json

@@ -17,6 +17,7 @@
   "main": "app/background.js",
   "build": {
     "appId": "com.beatplus.pronmail-desktop",
+    "afterPack": "scripts/after-pack.js",
     "publish": [
       "github"
     ],

scripts/after-pack.js

@@ -0,0 +1,55 @@
+// https://github.com/patrikx3/redis-ui/blob/b772176fc71f5cccbe1dbe31c8f7bd0fdb75f52e/src/build/after-pack.js
+
+const fs = require('fs-extra');
+const pkg = require('../package');
+const { spawn } = require('child_process');
+const { chdir } = require('process');
+
+const exec = async function exec(cmd, args = []) {
+  const child = spawn(cmd, args, { shell: true });
+  redirectOutputFor(child);
+  await waitFor(child);
+};
+
+const redirectOutputFor = (child) => {
+  const printStdout = (data) => {
+    process.stdout.write(data.toString());
+  };
+  const printStderr = (data) => {
+    process.stderr.write(data.toString());
+  };
+  child.stdout.on('data', printStdout);
+  child.stderr.on('data', printStderr);
+
+  child.once('close', () => {
+    child.stdout.off('data', printStdout);
+    child.stderr.off('data', printStderr);
+  });
+};
+
+const waitFor = async function(child) {
+  return new Promise((resolve) => {
+    child.once('close', () => resolve());
+  });
+};
+
+module.exports = async function(context) {
+  // eslint-disable-next-line no-console
+  console.warn('after build; disable sandbox');
+  const isLinux = context.targets.find(target => target.name === 'appImage' || target.name === 'snap');
+  if (!isLinux) {
+    return;
+  }
+  const originalDir = process.cwd();
+  const dirname = context.appOutDir;
+  chdir(dirname);
+
+  await exec('mv', [pkg.name, pkg.name + '.bin']);
+  const wrapperScript = `#!/bin/bash
+    "\${BASH_SOURCE%/*}"/${pkg.name}.bin "$@" --no-sandbox
+  `;
+  fs.writeFileSync(pkg.name, wrapperScript);
+  await exec('chmod', ['+x', pkg.name]);
+
+  chdir(originalDir);
+};