Enable strictNullChecks, eqeqeq (#436)

## Description:

Improve type safety and runtime correctness by:
1. Enabling TypeScript's
[strictNullChecks](https://www.typescriptlang.org/tsconfig/#strictNullChecks)
compiler option.
2. Replacing all loose equality operators (`==` and `!=`) with strict
equality operators (`===` and `!==`).
3. Cleaning up of type declarations, null handling logic, and equality
expressions throughout the project.

Currently, the code allows implicit assumptions that `null` and
`undefined` are interchangeable, and relies on type-coercing equality
checks that can introduce subtle bugs. These practices make it difficult
to reason about when values may be absent and hinder the effectiveness
of static analysis.

Migrating to strict null checks and enforcing strict equality
comparisons will clarify intent, reduce bugs, and make the codebase
safer and easier to maintain.

Fixes #466 

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [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

---------

Co-authored-by: Scott Anderson <662325+scottanderson@users.noreply.github.com>
Co-authored-by: evanpelle <openfrontio@gmail.com>

src/core/execution/WinCheckExecution.ts

@@ -15,7 +15,7 @@ export class WinEvent implements GameEvent {
 export class WinCheckExecution implements Execution {
   private active = true;
 
-  private mg: Game;
+  private mg: Game | null = null;
 
   constructor() {}
 
@@ -24,10 +24,11 @@ export class WinCheckExecution implements Execution {
   }
 
   tick(ticks: number) {
-    if (ticks % 10 != 0) {
+    if (ticks % 10 !== 0) {
       return;
     }
-    if (this.mg.config().gameConfig().gameMode == GameMode.FFA) {
+    if (this.mg === null) throw new Error("Not initialized");
+    if (this.mg.config().gameConfig().gameMode === GameMode.FFA) {
       this.checkWinnerFFA();
     } else {
       this.checkWinnerTeam();
@@ -35,10 +36,11 @@ export class WinCheckExecution implements Execution {
   }
 
   checkWinnerFFA(): void {
+    if (this.mg === null) throw new Error("Not initialized");
     const sorted = this.mg
       .players()
       .sort((a, b) => b.numTilesOwned() - a.numTilesOwned());
-    if (sorted.length == 0) {
+    if (sorted.length === 0) {
       return;
     }
     const max = sorted[0];
@@ -55,17 +57,21 @@ export class WinCheckExecution implements Execution {
   }
 
   checkWinnerTeam(): void {
+    if (this.mg === null) throw new Error("Not initialized");
     const teamToTiles = new Map<Team, number>();
     for (const player of this.mg.players()) {
+      const team = player.team();
+      // Sanity check, team should not be null here
+      if (team === null) continue;
       teamToTiles.set(
-        player.team(),
-        (teamToTiles.get(player.team()) ?? 0) + player.numTilesOwned(),
+        team,
+        (teamToTiles.get(team) ?? 0) + player.numTilesOwned(),
       );
     }
     const sorted = Array.from(teamToTiles.entries()).sort(
       (a, b) => b[1] - a[1],
     );
-    if (sorted.length == 0) {
+    if (sorted.length === 0) {
       return;
     }
     const max = sorted[0];
@@ -73,15 +79,12 @@ export class WinCheckExecution implements Execution {
       this.mg.numLandTiles() - this.mg.numTilesWithFallout();
     const percentage = (max[1] / numTilesWithoutFallout) * 100;
     if (percentage > this.mg.config().percentageTilesOwnedToWin()) {
-      if (max[0] == ColoredTeams.Bot) return;
+      if (max[0] === ColoredTeams.Bot) return;
       this.mg.setWinner(max[0], this.mg.stats().stats());
       console.log(`${max[0]} has won the game`);
       this.active = false;
     }
   }
-  owner(): Player {
-    return null;
-  }
 
   isActive(): boolean {
     return this.active;