Enable @typescript eslint/prefer nullish coalescing eslint rule (#1420)

## Description:

Fixes #952 
Enabled @typescript-eslint/prefer-nullish-coalescing rule and worked
through every error, introducing ?? and ??= operators or disabling
errors with inline comments where appropriate, to the best of my
ability.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

g_santos_m

src/server/Archive.ts

@@ -37,7 +37,7 @@ export async function archive(gameRecord: GameRecord) {
     }
   } catch (error) {
     log.error(`${gameRecord.info.gameID}: Final archive error: ${error}`, {
-      message: error?.message || error,
+      message: error?.message ?? error,
       stack: error?.stack,
       name: error?.name,
       ...(error && typeof error === "object" ? error : {}),
@@ -70,7 +70,7 @@ async function archiveAnalyticsToR2(gameRecord: GameRecord) {
     log.info(`${info.gameID}: successfully wrote game analytics to R2`);
   } catch (error) {
     log.error(`${info.gameID}: Error writing game analytics to R2: ${error}`, {
-      message: error?.message || error,
+      message: error?.message ?? error,
       stack: error?.stack,
       name: error?.name,
       ...(error && typeof error === "object" ? error : {}),
@@ -119,7 +119,7 @@ export async function readGameRecord(
   } catch (error) {
     // Log the error for monitoring purposes
     log.error(`${gameId}: Error reading game record from R2: ${error}`, {
-      message: error?.message || error,
+      message: error?.message ?? error,
       stack: error?.stack,
       name: error?.name,
       ...(error && typeof error === "object" ? error : {}),
@@ -142,7 +142,7 @@ export async function gameRecordExists(gameId: GameID): Promise<boolean> {
       return false;
     }
     log.error(`${gameId}: Error checking archive existence: ${error}`, {
-      message: error?.message || error,
+      message: error?.message ?? error,
       stack: error?.stack,
       name: error?.name,
       ...(error && typeof error === "object" ? error : {}),

src/server/Cloudflare.ts

@@ -162,7 +162,9 @@ export class Cloudflare {
     );
 
     const credentials = {
+      // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
       AccountTag: tokenData.a || this.accountId,
+      // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
       TunnelID: tokenData.t || tunnelId,
       TunnelName: tunnelName,
       TunnelSecret: tokenData.s,

src/server/GameServer.ts

@@ -694,7 +694,7 @@ export class GameServer {
     for (const client of this.activeClients) {
       if (client.hashes.has(turnNumber)) {
         const clientHash = client.hashes.get(turnNumber)!;
-        counts.set(clientHash, (counts.get(clientHash) || 0) + 1);
+        counts.set(clientHash, (counts.get(clientHash) ?? 0) + 1);
       }
     }
 

src/server/Master.ts

@@ -146,8 +146,9 @@ app.get(
   "/api/env",
   gatekeeper.httpHandler(LimiterType.Get, async (req, res) => {
     const envConfig = {
-      game_env: process.env.GAME_ENV || "prod",
+      game_env: process.env.GAME_ENV,
     };
+    if (!envConfig.game_env) return res.sendStatus(500);
     res.json(envConfig);
   }),
 );

src/server/Worker.ts

@@ -29,7 +29,7 @@ import { initWorkerMetrics } from "./WorkerMetrics";
 
 const config = getServerConfigFromServer();
 
-const workerId = parseInt(process.env.WORKER_ID || "0");
+const workerId = parseInt(process.env.WORKER_ID ?? "0");
 const log = logger.child({ comp: `w_${workerId}` });
 
 // Worker setup
@@ -94,6 +94,7 @@ export function startWorker() {
         log.warn(`cannot create game, id not found`);
         return res.status(400).json({ error: "Game ID is required" });
       }
+      // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
       const clientIP = req.ip || req.socket.remoteAddress || "unknown";
       const result = CreateGameInputSchema.safeParse(req.body);
       if (!result.success) {
@@ -140,6 +141,7 @@ export function startWorker() {
         return;
       }
       if (game.isPublic()) {
+        // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
         const clientIP = req.ip || req.socket.remoteAddress || "unknown";
         log.info(
           `cannot start public game ${game.id}, game is public, ip: ${ipAnonymize(clientIP)}`,
@@ -171,6 +173,7 @@ export function startWorker() {
         return res.status(400).json({ error: "Game not found" });
       }
       if (game.isPublic()) {
+        // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
         const clientIP = req.ip || req.socket.remoteAddress || "unknown";
         log.warn(
           `cannot update public game ${game.id}, ip: ${ipAnonymize(clientIP)}`,
@@ -296,7 +299,8 @@ export function startWorker() {
         const forwarded = req.headers["x-forwarded-for"];
         const ip = Array.isArray(forwarded)
           ? forwarded[0]
-          : forwarded || req.socket.remoteAddress || "unknown";
+          : // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
+            forwarded || req.socket.remoteAddress || "unknown";
 
         try {
           // Parse and handle client messages