[CLEANUP] Some fixes so that Day4 could be deployed to firebase

functions/src/day4.ts

@@ -8,7 +8,7 @@ class Day4 implements Day {
     const { drawnNumbers, bingoCards } = this.parseInput(input);
 
     // We are done as soon as we encounter the first bingo
-    return this.playBingo(drawnNumbers, bingoCards, b => ({ isDone: true }) ).score;
+    return this.playBingo(drawnNumbers, bingoCards, _ => ({ isDone: true }) ).score;
   }
 
   part2(input: string[]): number | string {
@@ -24,7 +24,7 @@ class Day4 implements Day {
   playBingo(drawnNumbers: number[], bingoCards: BingoCard[], bingoHandler: (b: Bingo, bingoCard: BingoCard, allCards: BingoCard[]) => { isDone: boolean }): Bingo {
 
     for (const draw of drawnNumbers) {
-      for (let bingoCard of bingoCards) {
+      for (const bingoCard of bingoCards) {
         const cardResult = bingoCard.cross(draw);
         if (cardResult instanceof Bingo) {
           const handleResult = bingoHandler(cardResult, bingoCard, bingoCards);