I see this error with the app, reported by NextJS, please fix it. The er

src/components/cost-estimator/cost-estimator-form.tsx

@@ -1,3 +1,4 @@
+
 "use client";
 
 import React, { useState, useTransition, useMemo } from 'react';
@@ -10,7 +11,8 @@ import { Step6Animations } from './step-6-animations';
 import { Step7Illustrations } from './step-7-illustrations';
 import { Step8Branding } from './step-8-branding';
 import { Step9AdditionalFeatures } from './step-9-additional-features';
-import { Step10Results, calculateTotalHours } from './step-10-results';
+import { Step10ShoppingCart } from './step-10-shopping-cart';
+import { Step11Results, calculateTotalHours } from './step-11-results';
 import { Card, CardContent } from '@/components/ui/card';
 import { AnimatePresence, motion } from 'framer-motion';
 
@@ -33,6 +35,7 @@ export type FormData = {
   illustrations: IllustrationSelection;
   branding: BrandingSelection;
   additionalFeatures: string[];
+  shoppingCart: boolean | null;
 };
 
 export function CostEstimatorForm() {
@@ -52,6 +55,7 @@ export function CostEstimatorForm() {
     },
     branding: null,
     additionalFeatures: [],
+    shoppingCart: null,
   });
   const [isPending, startTransition] = useTransition();
 
@@ -87,6 +91,7 @@ export function CostEstimatorForm() {
         },
         branding: null,
         additionalFeatures: [],
+        shoppingCart: null,
     });
     setCurrentStep(1);
   }
@@ -177,7 +182,16 @@ export function CostEstimatorForm() {
         );
       case 10:
         return (
-            <Step10Results
+          <Step10ShoppingCart
+            onNext={handleNextStep}
+            onBack={handlePrevStep}
+            onUpdateData={handleUpdateFormData}
+            formData={formData}
+          />
+        );
+      case 11:
+        return (
+            <Step11Results
                 formData={formData}
                 onReset={handleReset}
                 estimatedHours={estimatedHours}

src/components/cost-estimator/step-10-shopping-cart.tsx

@@ -0,0 +1,123 @@
+
+"use client";
+
+import type { FormData } from './cost-estimator-form';
+import { Button } from '@/components/ui/button';
+import { Gauge } from 'lucide-react';
+import React, { useState, useMemo } from 'react';
+
+type Step10Props = {
+  onNext: () => void;
+  onBack: () => void;
+  onUpdateData: (data: Partial<FormData>) => void;
+  formData: FormData;
+};
+
+const designHoursMap = { custom: 60, mockups: 30, existing: 0 };
+const illustrationHoursMap = { '2d_static': 10, '2d_animated': 25, '3d_static': 20, '3d_animated': 40 };
+const brandingHoursMap = { 'full-cycle': 70, 'brush-up': 30, 'logo-only': 20, 'none': 0 };
+const featuresHoursMap: Record<string, number> = {
+  'registration': 10,
+  'member-profiles': 20,
+  'admin-panel': 28,
+  'crm-integration': 31,
+  'dashboard': 40,
+  'blog': 35,
+  'event-scheduling': 35,
+  'reservations': 35,
+  'chat-live-chat': 50,
+  'image-video-galleries': 5,
+  'location-based': 40,
+  'live-streaming': 55,
+};
+const shoppingCartHours = 45;
+
+const calculateHours = (
+    formData: FormData,
+    shoppingCart: boolean | null
+): number => {
+    const pageVal = formData.pageCount === 10 ? 50 : (formData.pageCount + 1) * 5 - 1;
+    const pageHours = pageVal * 6;
+    const stageHours = Math.round((formData.projectStage / 100) * 50);
+    const designHours = formData.designProcess ? designHoursMap[formData.designProcess] : 0;
+    const animationHours = formData.animatedElements ? 30 : 0;
+
+    let illustrationTotalHours = 0;
+    if (formData.illustrations.has2d) {
+        if (formData.illustrations.is2dAnimated === 'static') illustrationTotalHours += illustrationHoursMap['2d_static'];
+        if (formData.illustrations.is2dAnimated === 'animated') illustrationTotalHours += illustrationHoursMap['2d_animated'];
+    }
+    if (formData.illustrations.has3d) {
+        if (formData.illustrations.is3dAnimated === 'static') illustrationTotalHours += illustrationHoursMap['3d_static'];
+        if (formData.illustrations.is3dAnimated === 'animated') illustrationTotalHours += illustrationHoursMap['3d_animated'];
+    }
+
+    const brandingH = formData.branding ? (brandingHoursMap[formData.branding] ?? 0) : 0;
+    
+    const additionalFeaturesHours = formData.additionalFeatures.reduce((total, feature) => {
+        return total + (featuresHoursMap[feature] || 0);
+    }, 0);
+
+    const cartHours = shoppingCart ? shoppingCartHours : 0;
+
+    return pageHours + stageHours + designHours + animationHours + illustrationTotalHours + brandingH + additionalFeaturesHours + cartHours;
+};
+
+export function Step10ShoppingCart({ onNext, onBack, onUpdateData, formData }: Step10Props) {
+  const [selectedOption, setSelectedOption] = useState<boolean | null>(formData.shoppingCart);
+
+  const handleSelect = (option: boolean) => {
+    setSelectedOption(option);
+    onUpdateData({ shoppingCart: option });
+  };
+
+  const estimatedHours = useMemo(() => {
+    return calculateHours(formData, selectedOption);
+  }, [selectedOption, formData]);
+
+  return (
+    <div className="flex flex-col items-start">
+      <h2 className="font-headline text-3xl font-bold tracking-tight text-center w-full">Do you need a shopping cart for buying multiple products with one check-out?</h2>
+      <div className="mt-8 grid w-full grid-cols-1 gap-4 md:grid-cols-2">
+        <Button
+            variant={selectedOption === true ? 'default' : 'outline'}
+            className="w-full justify-start p-6 text-lg"
+            onClick={() => handleSelect(true)}
+        >
+            Yes
+        </Button>
+        <Button
+            variant={selectedOption === false ? 'default' : 'outline'}
+            className="w-full justify-start p-6 text-lg"
+            onClick={() => handleSelect(false)}
+        >
+            No
+        </Button>
+      </div>
+      <div className="mt-16 flex w-full items-center justify-between">
+        <div className="flex items-center gap-2">
+            <Gauge className="h-6 w-6 text-primary" />
+            <span className="font-headline text-lg font-bold">{estimatedHours}+ hours</span>
+        </div>
+        <div className="flex items-center gap-4">
+            <Button variant="ghost" onClick={onBack}>Back</Button>
+            <div className="flex items-center gap-2">
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-primary rounded-full" />
+            </div>
+            <Button onClick={onNext} disabled={selectedOption === null}>
+              Submit
+            </Button>
+        </div>
+      </div>
+    </div>
+  );
+}

src/components/cost-estimator/step-11-results.tsx

@@ -1,4 +1,3 @@
-
 "use client";
 
 import type { FormData } from './cost-estimator-form';
@@ -7,7 +6,7 @@ import { Card, CardContent, CardHeader, CardTitle, CardDescription } from '@/com
 import { PartyPopper, RefreshCw } from 'lucide-react';
 import React from 'react';
 
-type Step10Props = {
+type Step11Props = {
   formData: FormData;
   onReset: () => void;
   estimatedHours: number;
@@ -30,6 +29,7 @@ const featuresHoursMap: Record<string, number> = {
   'location-based': 40,
   'live-streaming': 55,
 };
+const shoppingCartHours = 45;
 
 
 export const calculateTotalHours = (formData: FormData): number => {
@@ -55,12 +55,14 @@ export const calculateTotalHours = (formData: FormData): number => {
         return total + (featuresHoursMap[feature] || 0);
     }, 0);
 
-    return pageHours + stageHours + designHours + animationHours + illustrationTotalHours + brandingH + additionalFeaturesHours;
+    const cartHours = formData.shoppingCart ? shoppingCartHours : 0;
+
+    return pageHours + stageHours + designHours + animationHours + illustrationTotalHours + brandingH + additionalFeaturesHours + cartHours;
 };
 
 const HOURLY_RATE = 75; // Example hourly rate in USD
 
-export function Step10Results({ formData, onReset, estimatedHours }: Step10Props) {
+export function Step11Results({ formData, onReset, estimatedHours }: Step11Props) {
   
   const estimatedCost = estimatedHours * HOURLY_RATE;
 

src/components/cost-estimator/step-8-branding.tsx

@@ -102,6 +102,7 @@ export function Step8Branding({ onNext, onBack, onUpdateData, formData }: Step8P
               <div className="w-10 h-2 bg-primary rounded-full" />
               <div className="w-10 h-2 bg-primary rounded-full" />
               <div className="w-10 h-2 bg-muted rounded-full" />
+               <div className="w-10 h-2 bg-muted rounded-full" />
             </div>
             <Button onClick={onNext} disabled={selected === null}>
               Next

src/components/cost-estimator/step-9-additional-features.tsx

@@ -126,9 +126,10 @@ export function Step9AdditionalFeatures({ onNext, onBack, onUpdateData, formData
               <div className="w-10 h-2 bg-primary rounded-full" />
               <div className="w-10 h-2 bg-primary rounded-full" />
               <div className="w-10 h-2 bg-primary rounded-full" />
+              <div className="w-10 h-2 bg-muted rounded-full" />
             </div>
             <Button onClick={onNext}>
-              See Results
+              Next
             </Button>
         </div>
       </div>