diff --git a/src/app/api/goals/route.ts b/src/app/api/goals/route.ts
index 0d616ebd3..84218a34a 100644
--- a/src/app/api/goals/route.ts
+++ b/src/app/api/goals/route.ts
@@ -177,7 +177,7 @@ export async function GET() {
     }
   }
 
-  const goalsWithHistory = processedGoals.map((goal) => ({
+  const goalsWithHistory = (processedGoals ?? []).map((goal) => ({
     ...goal,
     last_period: latestHistoryByGoal.get(goal.id) ?? null,
   }));
@@ -239,7 +239,7 @@ try {
   let safeDeadline: string | null = null;
   if (typeof deadline === "string") {
     const d = new Date(deadline);
-    if (!isNaN(d.getTime())) {
+    if (!Number.isNaN(d.getTime())) {
       d.setUTCHours(23, 59, 59, 999);
       safeDeadline = d.toISOString();
     }
diff --git a/src/components/GoalTracker.tsx b/src/components/GoalTracker.tsx
index d2eecbe22..51a010c77 100644
--- a/src/components/GoalTracker.tsx
+++ b/src/components/GoalTracker.tsx
@@ -429,7 +429,7 @@ export default function GoalTracker() {
       const data: { goal: Goal } = await response.json();
 
       setGoals((currentGoals) =>
-        currentGoals.map((goal) => (goal.id === data.goal.id ? data.goal : goal))
+        (currentGoals ?? []).map((goal) => (goal.id === data.goal.id ? data.goal : goal))
       );
     } catch {
       setShareError("Failed to update goal sharing. Please check your connection.");
@@ -586,7 +586,7 @@ export default function GoalTracker() {
               >
                 All
               </button>
-              {CATEGORY_OPTIONS.map((c) => (
+              {(CATEGORY_OPTIONS ?? []).map((c) => (
                 <button
                   key={c}
                   type="button"
@@ -1064,7 +1064,7 @@ function ConfettiBurst() {
         id: i,
         x: Math.cos(angle) * distance,
         y: Math.sin(angle) * distance - 20,
-        color: colors[Math.random() * colors.length | 0],
+        color: colors[Math.floor(Math.random() * colors.length) | 0],
         rot: Math.random() * 360 + 180,
         scale: 0.5 + Math.random() * 0.7,
         speed: 0.8 + Math.random() * 0.6,