refactor: move Twitch channel name to environment variable

Author: alexbcberio

.env.example

@@ -1,2 +1,6 @@
+# ID of Twitch application
 TWITCH_CLIENT_ID=
-TWITCH_CLIENT_SECRET=
+# Secret of Twitch application
+TWITCH_CLIENT_SECRET=
+# Username of the channel where it will connect and listen for events
+TWITCH_CHANNEL_NAME=

README.md

@@ -57,6 +57,7 @@ The file content of the file should be something similar to this:
 ```env
 TWITCH_CLIENT_ID=theClientIdProvidedByTwitch
 TWITCH_CLIENT_SECRET=aSecretYouHaveToKeepSafe
+TWITCH_CHANNEL_NAME=<username of the Twitch streamer>
 ```
 
 ### Create OAuth2 user token

src/backend/index.ts

@@ -2,13 +2,22 @@ import { connect } from "./chatClient";
 import { listen } from "./helpers/webServer";
 import { registerUserListener } from "./pubSubClient";
 
-const channel = "alexbcberio";
+const LOG_PREFIX = "[APP] ";
+
+const channel = process.env.TWITCH_CHANNEL_NAME;
 
 export async function bootstrap() {
-  await Promise.all([
-    registerUserListener(channel),
-    connect([channel]),
-  ]);
+  if (!channel) {
+    console.error(
+      `${LOG_PREFIX}Missing environment parameter TWITCH_CHANNEL_NAME`
+    );
+
+    const errorCode = 1;
+
+    process.exit(errorCode);
+  }
+
+  await Promise.all([registerUserListener(channel), connect([channel])]);
 
   listen();
-}
+}