bugfix: remove unit before updating tile in UnitImpl.move(). This is because if a unit moves too fast or on border, UnitGrid will not find the existing unit, causing duplicate units

src/core/game/UnitImpl.ts

@@ -88,9 +88,9 @@ export class UnitImpl implements Unit {
     if (tile == null) {
       throw new Error("tile cannot be null");
     }
+    this.mg.removeUnit(this);
     this._lastTile = this._tile;
     this._tile = tile;
-    this.mg.removeUnit(this);
     this.mg.addUnit(this);
     this.mg.addUpdate(this.toUpdate());
   }