Validate spawn tile (#1512)

## Description:

Enforce valid tile during spawn, to prevent the game from crashing for
all players.

## 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
- [ ] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [ ] I have read and accepted the CLA aggreement (only required once).

src/core/execution/ConstructionExecution.ts

@@ -1,5 +1,4 @@
 import {
-  Cell,
   Execution,
   Game,
   Gold,
@@ -27,12 +26,11 @@ export class ConstructionExecution implements Execution {
   private ticksUntilComplete: Tick;
 
   private cost: Gold;
-  private tile: TileRef;
 
   constructor(
     private player: Player,
     private constructionType: UnitType,
-    private tileOrCell: TileRef | Cell,
+    private tile: TileRef,
   ) {}
 
   init(mg: Game, ticks: number): void {
@@ -46,17 +44,10 @@ export class ConstructionExecution implements Execution {
       return;
     }
 
-    if (this.tileOrCell instanceof Cell) {
-      if (!this.mg.isValidCoord(this.tileOrCell.x, this.tileOrCell.y)) {
-        console.warn(
-          `cannot build construction invalid coordinates ${this.tileOrCell.x}, ${this.tileOrCell.y}`,
-        );
-        this.active = false;
-        return;
-      }
-      this.tile = this.mg.ref(this.tileOrCell.x, this.tileOrCell.y);
-    } else {
-      this.tile = this.tileOrCell;
+    if (!this.mg.isValidRef(this.tile)) {
+      console.warn(`cannot build construction invalid tile ${this.tile}`);
+      this.active = false;
+      return;
     }
   }
 

src/core/execution/ExecutionManager.ts

@@ -1,4 +1,4 @@
-import { Cell, Execution, Game } from "../game/Game";
+import { Execution, Game } from "../game/Game";
 import { PseudoRandom } from "../PseudoRandom";
 import { ClientID, GameID, Intent, Turn } from "../Schemas";
 import { simpleHash } from "../Util";
@@ -67,10 +67,7 @@ export class Executor {
       case "move_warship":
         return new MoveWarshipExecution(player, intent.unitId, intent.tile);
       case "spawn":
-        return new SpawnExecution(
-          player.info(),
-          this.mg.ref(intent.x, intent.y),
-        );
+        return new SpawnExecution(player.info(), intent.tile);
       case "boat":
         return new TransportShipExecution(
           player,
@@ -106,11 +103,7 @@ export class Executor {
       case "embargo":
         return new EmbargoExecution(player, intent.targetID, intent.action);
       case "build_unit":
-        return new ConstructionExecution(
-          player,
-          intent.unit,
-          new Cell(intent.x, intent.y),
-        );
+        return new ConstructionExecution(player, intent.unit, intent.tile);
       case "allianceExtension": {
         return new AllianceExtensionExecution(player, intent.recipient);
       }

src/core/execution/SpawnExecution.ts

@@ -20,6 +20,11 @@ export class SpawnExecution implements Execution {
   tick(ticks: number) {
     this.active = false;
 
+    if (!this.mg.isValidRef(this.tile)) {
+      console.warn(`SpawnExecution: tile ${this.tile} not valid`);
+      return;
+    }
+
     if (!this.mg.inSpawnPhase()) {
       this.active = false;
       return;