Help please with this error

VF:
<apex:page controller="XSS_Visualforce_Mitigations_Demo" sidebar="false" tabStyle="XSS_Visualforce_Mitigations_Demo__tab" action="{!seedURL}"> <apex:sectionHeader title="XSS Visualforce Mitigations Demo" /> <apex:form > <apex:pageBlock > <c:Classic_Error /> <apex:pageMessages /> <apex:pageBlockSection title="Demo" columns="1" id="tableBlock"> <apex:outputPanel > <apex:outputText value="Welcome, {!HTMLENCODE($CurrentPage.Parameters.user)}! "/> <apex:outputText value="You are viewing the castle friend finder! We have randomly selected a friend for you."/><br/> <apex:outputText id="output1" value=""/> <apex:outputText id="output2" value=""/> <script> var vip = '{!JSENCODE(title)}'; if(vip!=''){ document.getElementById('{!$Component.output1}').innerHTML = '<br/>This person is a: <br/>&nbsp;-----<br/>| VIP |<br/>&nbsp;-----<br/>LUCKY YOU!'; } else { document.getElementById('{!$Component.output1}').innerHTML = '<br/>This person is a peasant'; } var html = '<br/><br/><b>---------------------</b>'; html += '<br/>Personnel Name: {!JSINHTMLENCODE(name)}'; html += '<br/>Favorite color: {!JSINHTMLENCODE(color)}'; html += '<br/>Favorite animal: {!JSINHTMLENCODE(animal)}'; html += '<br/><b>---------------------</b>'; document.getElementById('{!$Component.output2}').innerHTML = html; </script> </apex:outputPanel> <apex:outputPanel > <br/><br/> <apex:commandButton value="Click here to view the JavaScript based XSS!" action="{!JSXSS}"/> <apex:commandButton value="Click here to view the HTML based XSS!" action="{!HTMLXSS}"/> <apex:commandButton value="Click here to view the Javascript + HTML based XSS!" action="{!JSINHTMLXSS}"/> <apex:commandButton value="Remove All XSS" action="{!REMOVEXSS}"/> </apex:outputPanel> </apex:pageBlockSection> <apex:pageBlockSection title="Code links" columns="1"> <apex:outputPanel > <ul> <li><c:codeLink type="Visualforce" namespace="security_thail" name="XSS_Visualforce_Mitigations_Demo" description="Visualforce Page"/></li> <li><c:codeLink type="Apex" namespace="security_thail" name="XSS_Visualforce_Mitigations_Demo" description="Apex Controller"/></li> </ul> </apex:outputPanel> </apex:pageBlockSection> </apex:pageBlock> </apex:form> </apex:page>


Apex:
public class XSS_Visualforce_Mitigations_Demo {

    public string hello {get; set;}
    public string title {get;set;}
    public string name {get;set;}
    public string color {get;set;}
    public string animal {get;set;}
    public Personnel__c person;

    public pageReference seedURL(){
        pageReference p = page.XSS_Visualforce_Mitigations_Demo;
        String user = ApexPages.currentPage().getParameters().get('user');
        if(string.isBlank(user)){      
            p.getParameters().put('user',userinfo.getName());
            p.setRedirect(true);
        } else {
            p.getParameters().put('user',user);
        }

        if(p.getRedirect()==true){
            return p;
        } else {
            return null; 
        }
        
    }   

    public XSS_Visualforce_Mitigations_Demo(){
        person = [SELECT Favorite_Animal__c,Favorite_Color__c,Id,Name,Title__c FROM Personnel__c where Favorite_Animal__c!=null and Favorite_Color__c!=null limit 1];
        title = person.title__c;
        // adding to fix demo steps...          
        title = '<b>' + ESAPI.encoder().SFDC_HTMLENCODE(person.Title__c) +'</b>';

        name = person.name;
        color = person.favorite_color__c;
        animal = person.favorite_animal__c;
        hello = ApexPages.currentPage().getParameters().get('user');
    }

    public pageReference HTMLXSS(){
        pageReference p = page.XSS_Visualforce_Mitigations_Demo;
        p.getParameters().put('user',ESAPI.encoder().SFDC_HTMLENCODE(person.name));
        p.setRedirect(true);
        return p;
    }

    public pageReference JSXSS(){
        title = ESAPI.encoder().SFDC_HTMLENCODE(person.Title__c);
        return null;
    }

    public pageReference JSINHTMLXSS(){
    color = ESAPI.encoder().SFDC_HTMLENCODE(person.favorite_color__c);
    return null;
}


    
    public pageReference REMOVEXSS(){
        pageReference p = page.XSS_Visualforce_Mitigations_Demo;
        p.getParameters().put('user',userinfo.getName());              
        title = person.title__c;
        color = person.Favorite_Color__c;
        p.setRedirect(true);
        return p;
    }    

}

Error:It doesn't appear that you've fixed all of the merge fields to prevent cross-site scripting vectors. Please check your code again.

I have Estimates__c,Project_c
Project.Estimated_Hours__c should have sum of Estimates__c.Total_Hours__c on id,
Trigger should be on Estimates__c(after insert)
, Estimates__c.Project__c link to Project_c

PLS HELP
I am begginer

Assign the fields of one object to another. and  update data of Project_c

VF:
<apex:page controller="XSS_Visualforce_Mitigations_Demo" sidebar="false" tabStyle="XSS_Visualforce_Mitigations_Demo__tab" action="{!seedURL}"> <apex:sectionHeader title="XSS Visualforce Mitigations Demo" /> <apex:form > <apex:pageBlock > <c:Classic_Error /> <apex:pageMessages /> <apex:pageBlockSection title="Demo" columns="1" id="tableBlock"> <apex:outputPanel > <apex:outputText value="Welcome, {!HTMLENCODE($CurrentPage.Parameters.user)}! "/> <apex:outputText value="You are viewing the castle friend finder! We have randomly selected a friend for you."/><br/> <apex:outputText id="output1" value=""/> <apex:outputText id="output2" value=""/> <script> var vip = '{!JSENCODE(title)}'; if(vip!=''){ document.getElementById('{!$Component.output1}').innerHTML = '<br/>This person is a: <br/>&nbsp;-----<br/>| VIP |<br/>&nbsp;-----<br/>LUCKY YOU!'; } else { document.getElementById('{!$Component.output1}').innerHTML = '<br/>This person is a peasant'; } var html = '<br/><br/><b>---------------------</b>'; html += '<br/>Personnel Name: {!JSINHTMLENCODE(name)}'; html += '<br/>Favorite color: {!JSINHTMLENCODE(color)}'; html += '<br/>Favorite animal: {!JSINHTMLENCODE(animal)}'; html += '<br/><b>---------------------</b>'; document.getElementById('{!$Component.output2}').innerHTML = html; </script> </apex:outputPanel> <apex:outputPanel > <br/><br/> <apex:commandButton value="Click here to view the JavaScript based XSS!" action="{!JSXSS}"/> <apex:commandButton value="Click here to view the HTML based XSS!" action="{!HTMLXSS}"/> <apex:commandButton value="Click here to view the Javascript + HTML based XSS!" action="{!JSINHTMLXSS}"/> <apex:commandButton value="Remove All XSS" action="{!REMOVEXSS}"/> </apex:outputPanel> </apex:pageBlockSection> <apex:pageBlockSection title="Code links" columns="1"> <apex:outputPanel > <ul> <li><c:codeLink type="Visualforce" namespace="security_thail" name="XSS_Visualforce_Mitigations_Demo" description="Visualforce Page"/></li> <li><c:codeLink type="Apex" namespace="security_thail" name="XSS_Visualforce_Mitigations_Demo" description="Apex Controller"/></li> </ul> </apex:outputPanel> </apex:pageBlockSection> </apex:pageBlock> </apex:form> </apex:page>


Apex:
public class XSS_Visualforce_Mitigations_Demo {

    public string hello {get; set;}
    public string title {get;set;}
    public string name {get;set;}
    public string color {get;set;}
    public string animal {get;set;}
    public Personnel__c person;

    public pageReference seedURL(){
        pageReference p = page.XSS_Visualforce_Mitigations_Demo;
        String user = ApexPages.currentPage().getParameters().get('user');
        if(string.isBlank(user)){      
            p.getParameters().put('user',userinfo.getName());
            p.setRedirect(true);
        } else {
            p.getParameters().put('user',user);
        }

        if(p.getRedirect()==true){
            return p;
        } else {
            return null; 
        }
        
    }   

    public XSS_Visualforce_Mitigations_Demo(){
        person = [SELECT Favorite_Animal__c,Favorite_Color__c,Id,Name,Title__c FROM Personnel__c where Favorite_Animal__c!=null and Favorite_Color__c!=null limit 1];
        title = person.title__c;
        // adding to fix demo steps...          
        title = '<b>' + ESAPI.encoder().SFDC_HTMLENCODE(person.Title__c) +'</b>';

        name = person.name;
        color = person.favorite_color__c;
        animal = person.favorite_animal__c;
        hello = ApexPages.currentPage().getParameters().get('user');
    }

    public pageReference HTMLXSS(){
        pageReference p = page.XSS_Visualforce_Mitigations_Demo;
        p.getParameters().put('user',ESAPI.encoder().SFDC_HTMLENCODE(person.name));
        p.setRedirect(true);
        return p;
    }

    public pageReference JSXSS(){
        title = ESAPI.encoder().SFDC_HTMLENCODE(person.Title__c);
        return null;
    }

    public pageReference JSINHTMLXSS(){
    color = ESAPI.encoder().SFDC_HTMLENCODE(person.favorite_color__c);
    return null;
}


    
    public pageReference REMOVEXSS(){
        pageReference p = page.XSS_Visualforce_Mitigations_Demo;
        p.getParameters().put('user',userinfo.getName());              
        title = person.title__c;
        color = person.Favorite_Color__c;
        p.setRedirect(true);
        return p;
    }    

}

Error:It doesn't appear that you've fixed all of the merge fields to prevent cross-site scripting vectors. Please check your code again.

I have Estimates__c,Project_c
Project.Estimated_Hours__c should have sum of Estimates__c.Total_Hours__c on id,
Trigger should be on Estimates__c(after insert)
, Estimates__c.Project__c link to Project_c

PLS HELP
I am begginer

Assign the fields of one object to another. and  update data of Project_c