react-native.config.js handle optional @react-native-community dependencies

Summary:
As part of decoupling our dependency on the react-native-community/cli, the `react-native.config.js` which is
a part of the community's config ecosystem should probably be entirely removed from the react-native package.

As part of this, we're making the config fail gracefully if these dependencies aren't available in a user's project:

- react-native-community/cli-platform-android
- react-native-community/cli-platform-ios

Changelog: [Internal]

This isn't going to be a visible change to any users.

bypass-github-export-checks

Reviewed By: cortinico

Differential Revision: D56137820

fbshipit-source-id: 528e25809a83b90e79b806a875001fc0f06db1cf

packages/react-native/react-native.config.js

@@ -9,8 +9,39 @@
 
 'use strict';
 
-const android = require('@react-native-community/cli-platform-android');
-const ios = require('@react-native-community/cli-platform-ios');
+// React Native shouldn't be exporting itself like this, the Community Template should be be directly
+// depending on and injecting:
+// - @react-native-community/cli-platform-android
+// - @react-native-community/cli-platform-ios
+// - @react-native/community-cli-plugin (via the @react-native/core-cli-utils package)
+// - codegen command should be inhoused into @react-native-community/cli
+//
+// This is a temporary workaround.
+
+const verbose = process.env.DEBUG && process.env.DEBUG.includes('react-native');
+
+let android;
+try {
+  android = require('@react-native-community/cli-platform-android');
+} catch {
+  if (verbose) {
+    console.warn(
+      '@react-native-community/cli-platform-android not found, the react-native.config.js may be unusable.',
+    );
+  }
+}
+
+let ios;
+try {
+  ios = require('@react-native-community/cli-platform-ios');
+} catch {
+  if (verbose) {
+    console.warn(
+      '@react-native-community/cli-platform-ios not found, the react-native.config.js may be unusable.',
+    );
+  }
+}
+
 const {
   bundleCommand,
   startCommand,
@@ -43,22 +74,25 @@ const codegenCommand = {
     ),
 };
 
-module.exports = {
-  commands: [
-    ...ios.commands,
-    ...android.commands,
-    bundleCommand,
-    startCommand,
-    codegenCommand,
-  ],
-  platforms: {
-    ios: {
-      projectConfig: ios.projectConfig,
-      dependencyConfig: ios.dependencyConfig,
-    },
-    android: {
-      projectConfig: android.projectConfig,
-      dependencyConfig: android.dependencyConfig,
-    },
-  },
+const config = {
+  commands: [bundleCommand, startCommand, codegenCommand],
+  platforms: {},
 };
+
+if (ios != null) {
+  config.commands.push(...ios.commands);
+  config.platforms.ios = {
+    projectConfig: ios.projectConfig,
+    dependencyConfig: ios.dependencyConfig,
+  };
+}
+
+if (android != null) {
+  config.commands.push(...android.commands);
+  config.platforms.android = {
+    projectConfig: android.projectConfig,
+    dependencyConfig: android.dependencyConfig,
+  };
+}
+
+module.exports = config;