Install cross-platform deps before packaging

scripts/install-cross-deps.js

@@ -0,0 +1,30 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+/* eslint-disable no-console */
+
+const path = require('path');
+const { execSync } = require('child_process');
+
+exports.beforeBuild = async () => {
+  if (process.platform !== 'darwin') {
+    return true;
+  }
+
+  const nonNativeArchs = ['arm64', 'x64'].filter(arch => arch !== process.arch);
+
+  for (const arch of nonNativeArchs) {
+    console.log("Installing sharp's dependencies for", arch);
+    execSync('yarn run install', {
+      cwd: path.join(__dirname, '..', 'node_modules', 'sharp'),
+      env: {
+        ...process.env,
+        npm_config_arch: arch,
+      },
+    });
+  }
+
+  // Let electron-builder handle dependencies
+  return true;
+};
+
+exports.beforeBuild();