diff --git a/src/battle-scene.ts b/src/battle-scene.ts
index 656af1391fc..b2e5635b642 100644
--- a/src/battle-scene.ts
+++ b/src/battle-scene.ts
@@ -944,7 +944,7 @@ export default class BattleScene extends SceneBase {
   }
 
   randBattleSeedInt(range: integer, min: integer = 0): integer {
-    return this.currentBattle.randSeedInt(this, range, min);
+    return this.currentBattle?.randSeedInt(this, range, min);
   }
 
   reset(clearScene: boolean = false, clearData: boolean = false, reloadI18n: boolean = false): void {
@@ -2397,7 +2397,7 @@ export default class BattleScene extends SceneBase {
       }
 
       party.forEach((enemyPokemon: EnemyPokemon, i: integer) => {
-        const isBoss = enemyPokemon.isBoss() || (this.currentBattle.battleType === BattleType.TRAINER && this.currentBattle.trainer?.config.isBoss);
+        const isBoss = enemyPokemon.isBoss() || (this.currentBattle.battleType === BattleType.TRAINER && !!this.currentBattle.trainer?.config.isBoss);
         let upgradeChance = 32;
         if (isBoss) {
           upgradeChance /= 2;
@@ -2405,7 +2405,7 @@ export default class BattleScene extends SceneBase {
         if (isFinalBoss) {
           upgradeChance /= 8;
         }
-        const modifierChance = this.gameMode.getEnemyModifierChance(isBoss!); // TODO: is this bang correct?
+        const modifierChance = this.gameMode.getEnemyModifierChance(isBoss);
         let pokemonModifierChance = modifierChance;
         if (this.currentBattle.battleType === BattleType.TRAINER && this.currentBattle.trainer)
           pokemonModifierChance = Math.ceil(pokemonModifierChance * this.currentBattle.trainer.getPartyMemberModifierChanceMultiplier(i)); // eslint-disable-line
diff --git a/src/battle.ts b/src/battle.ts
index 0b3b256f3df..a82f1a3db9b 100644
--- a/src/battle.ts
+++ b/src/battle.ts
@@ -74,14 +74,14 @@ export default class Battle {
     this.gameMode = gameMode;
     this.waveIndex = waveIndex;
     this.battleType = battleType;
-    this.trainer = trainer!; //TODO: is this bang correct?
+    this.trainer = trainer ?? null;
     this.initBattleSpec();
     this.enemyLevels = battleType !== BattleType.TRAINER
       ? new Array(double ? 2 : 1).fill(null).map(() => this.getLevelForWave())
       : trainer?.getPartyLevels(this.waveIndex);
     this.enemyParty = [];
     this.seenEnemyPartyMemberIds = new Set<integer>();
-    this.double = double!; //TODO: is this bang correct?
+    this.double = !!double;
     this.enemySwitchCounter = 0;
     this.turn = 0;
     this.playerParticipantIds = new Set<integer>();
@@ -208,9 +208,9 @@ export default class Battle {
         return `encounter_${this.trainer?.getEncounterBgm()}`;
       }
       if (scene.musicPreference === 0) {
-        return this.trainer?.getBattleBgm()!; // TODO: is this bang correct?
+        return this.trainer?.getBattleBgm() ?? null;
       } else {
-        return this.trainer?.getMixedBattleBgm()!; // TODO: is this bang correct?
+        return this.trainer?.getMixedBattleBgm() ?? null;
       }
     } else if (this.gameMode.isClassic && this.waveIndex > 195 && this.battleSpec !== BattleSpec.FINAL_BOSS) {
       return "end_summit";
diff --git a/src/data/ability.ts b/src/data/ability.ts
index 054e32ad0ff..1840254d618 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -325,7 +325,7 @@ export class TypeImmunityAbAttr extends PreDefendAbAttr {
     super();
 
     this.immuneType = immuneType;
-    this.condition = condition!; // TODO: is this bang correct?
+    this.condition = condition ?? null;
   }
 
   /**
@@ -1507,7 +1507,7 @@ export class BattleStatMultiplierAbAttr extends AbAttr {
 
     this.battleStat = battleStat;
     this.multiplier = multiplier;
-    this.condition = condition!; // TODO: is this bang correct?
+    this.condition = condition ?? null;
   }
 
   applyBattleStat(pokemon: Pokemon, passive: boolean, battleStat: BattleStat, statValue: Utils.NumberHolder, args: any[]): boolean | Promise<boolean> {
@@ -1560,7 +1560,7 @@ export class PostAttackStealHeldItemAbAttr extends PostAttackAbAttr {
   constructor(stealCondition?: PokemonAttackCondition) {
     super();
 
-    this.stealCondition = stealCondition!; // TODO: is this bang correct?
+    this.stealCondition = stealCondition ?? null;
   }
 
   applyPostAttackAfterMoveTypeCheck(pokemon: Pokemon, passive: boolean, defender: Pokemon, move: Move, hitResult: HitResult, args: any[]): Promise<boolean> {
@@ -1649,7 +1649,7 @@ export class PostDefendStealHeldItemAbAttr extends PostDefendAbAttr {
   constructor(condition?: PokemonDefendCondition) {
     super();
 
-    this.condition = condition!; // TODO: is this bang correct?
+    this.condition = condition ?? null;
   }
 
   applyPostDefend(pokemon: Pokemon, passive: boolean, attacker: Pokemon, move: Move, hitResult: HitResult, args: any[]): Promise<boolean> {
@@ -2400,11 +2400,11 @@ export class ProtectStatAbAttr extends PreStatChangeAbAttr {
   constructor(protectedStat?: BattleStat) {
     super();
 
-    this.protectedStat = protectedStat!; // TODO: is this bang correct?
+    this.protectedStat = protectedStat ?? null;
   }
 
   applyPreStatChange(pokemon: Pokemon, passive: boolean, stat: BattleStat, cancelled: Utils.BooleanHolder, args: any[]): boolean {
-    if (this.protectedStat === undefined || stat === this.protectedStat) {
+    if (!this.protectedStat || stat === this.protectedStat) {
       cancelled.value = true;
       return true;
     }
@@ -2746,7 +2746,7 @@ export class SuppressWeatherEffectAbAttr extends PreWeatherEffectAbAttr {
   constructor(affectsImmutable?: boolean) {
     super();
 
-    this.affectsImmutable = affectsImmutable!; // TODO: is this bang correct?
+    this.affectsImmutable = !!affectsImmutable;
   }
 
   applyPreWeatherEffect(pokemon: Pokemon, passive: boolean, weather: Weather, cancelled: Utils.BooleanHolder, args: any[]): boolean {
@@ -2810,11 +2810,11 @@ function getAnticipationCondition(): AbAttrCondition {
           return true;
         }
         // move is a OHKO
-        if (move!.getMove().hasAttr(OneHitKOAttr)) { // TODO: is this bang correct?
+        if (move?.getMove().hasAttr(OneHitKOAttr)) {
           return true;
         }
         // edge case for hidden power, type is computed
-        if (move!.getMove().id === Moves.HIDDEN_POWER) { // TODO: is this bang correct?
+        if (move?.getMove().id === Moves.HIDDEN_POWER) {
           const iv_val = Math.floor(((opponent.ivs[Stat.HP] & 1)
               +(opponent.ivs[Stat.ATK] & 1) * 2
               +(opponent.ivs[Stat.DEF] & 1) * 4
@@ -2862,13 +2862,13 @@ export class ForewarnAbAttr extends PostSummonAbAttr {
     let movePower = 0;
     for (const opponent of pokemon.getOpponents()) {
       for (const move of opponent.moveset) {
-        if (move!.getMove() instanceof StatusMove) { // TODO: is this bang correct?
+        if (move?.getMove() instanceof StatusMove) {
           movePower = 1;
-        } else if (move!.getMove().hasAttr(OneHitKOAttr)) { // TODO: is this bang correct?
+        } else if (move?.getMove().hasAttr(OneHitKOAttr)) {
           movePower = 150;
-        } else if (move!.getMove().id === Moves.COUNTER || move!.getMove().id === Moves.MIRROR_COAT || move!.getMove().id === Moves.METAL_BURST) { // TODO: are those bangs correct?
+        } else if (move?.getMove().id === Moves.COUNTER || move?.getMove().id === Moves.MIRROR_COAT || move?.getMove().id === Moves.METAL_BURST) {
           movePower = 120;
-        } else if (move!.getMove().power === -1) { // TODO: is this bang correct?
+        } else if (move?.getMove().power === -1) {
           movePower = 80;
         } else {
           movePower = move!.getMove().power; // TODO: is this bang correct?
diff --git a/src/data/battle-anims.ts b/src/data/battle-anims.ts
index 634c39b7d66..c86f3db5085 100644
--- a/src/data/battle-anims.ts
+++ b/src/data/battle-anims.ts
@@ -683,8 +683,8 @@ export abstract class BattleAnim {
   private dstLine: number[];
 
   constructor(user?: Pokemon, target?: Pokemon) {
-    this.user = user!; // TODO: is this bang correct?
-    this.target = target!; // TODO: is this bang correct?
+    this.user = user ?? null;
+    this.target = target ?? null;
     this.sprites = [];
   }
 
diff --git a/src/data/daily-run.ts b/src/data/daily-run.ts
index b7e03b4b189..b875877f99e 100644
--- a/src/data/daily-run.ts
+++ b/src/data/daily-run.ts
@@ -19,7 +19,7 @@ export function fetchDailyRunSeed(): Promise<string | null> {
         return;
       }
       return response.text();
-    }).then(seed => resolve(seed!)) // TODO: is this bang correct?
+    }).then(seed => resolve(seed ?? null))
       .catch(err => reject(err));
   });
 }
diff --git a/src/inputs-controller.ts b/src/inputs-controller.ts
index 1af376ed6f4..7b0cb9cb050 100644
--- a/src/inputs-controller.ts
+++ b/src/inputs-controller.ts
@@ -343,7 +343,7 @@ export class InputsController {
     // Sometimes, gamepads are undefined. For some reason.
     this.gamepads = this.scene.input.gamepad?.gamepads.filter(function (el) {
       return el !== null;
-    })!; // TODO: is this bang correct?
+    }) ?? [];
 
     for (const [index, thisGamepad] of this.gamepads.entries()) {
       thisGamepad.index = index; // Overwrite the gamepad index, in case we had undefined gamepads earlier
diff --git a/src/messages.ts b/src/messages.ts
index b9bf94802f7..1cd6a5966b6 100644
--- a/src/messages.ts
+++ b/src/messages.ts
@@ -10,7 +10,8 @@ import i18next from "i18next";
 export function getPokemonNameWithAffix(pokemon: Pokemon | undefined): string {
   if (!pokemon) {
     return "Missigno";
-  } // TODO: little easter-egg, lol
+  }
+
   switch (pokemon.scene.currentBattle.battleSpec) {
   case BattleSpec.DEFAULT:
     return !pokemon.isPlayer()
diff --git a/src/phases.ts b/src/phases.ts
index 1d1a5e2473a..46d5ef36e3c 100644
--- a/src/phases.ts
+++ b/src/phases.ts
@@ -195,7 +195,7 @@ export class TitlePhase extends Phase {
 
     this.scene.playBgm("title", true);
 
-    this.scene.gameData.getSession(loggedInUser!.lastSessionSlot).then(sessionData => { // TODO: is this bang correct?
+    this.scene.gameData.getSession(loggedInUser?.lastSessionSlot ?? -1).then(sessionData => {
       if (sessionData) {
         this.lastSessionData = sessionData;
         const biomeKey = getBiomeKey(sessionData.arena.biome);
@@ -394,7 +394,11 @@ export class TitlePhase extends Phase {
       // If Online, calls seed fetch from db to generate daily run. If Offline, generates a daily run based on current date.
       if (!Utils.isLocal) {
         fetchDailyRunSeed().then(seed => {
-          generateDaily(seed!); // TODO: is this bang correct?
+          if (seed) {
+            generateDaily(seed);
+          } else {
+            throw new Error("Daily run seed is null!");
+          }
         }).catch(err => {
           console.error("Failed to load daily run:\n", err);
         });
@@ -468,7 +472,7 @@ export class ReloadSessionPhase extends Phase {
   constructor(scene: BattleScene, systemDataStr?: string) {
     super(scene);
 
-    this.systemDataStr = systemDataStr!; // TODO: is this bang correct?
+    this.systemDataStr = systemDataStr ?? null;
   }
 
   start(): void {