I have a user case where the community user needs to see all the appointments of all the contacts from their parent account.Here is the Code I have:
 

public class AppointmentListController {

public String AppFilterId {get; set;}
private Integer pageSize = 10;
private String baseQuery ='SELECT Name, contact.name, Status__c FROM appointment__c WHERE contact IN (SELECT Id FROM Contact WHERE AccountId = :myContact.AccountId)';

public AppointmentListController(){
    Contact myContact=[select id,accountid from contact where id in(select contactId from user where id=:userinfo.getuserid())];
}

public ApexPages.StandardSetController AppSetController {
    get{
        if(AppSetController == null){
            AppSetController = new ApexPages.StandardSetController(Database.getQueryLocator(baseQuery));
            AppSetController.setPageSize(pageSize);
            if(AppFilterId != null)
            {
                AppSetController.setFilterId(AppFilterId);
            }
        }
        return AppSetController;
    }set;
}

public AppointmentListController(ApexPages.StandardSetController c) {   }

public void firstPage()
{
    AppSetController.first();
}

public void lastPage()
{
    AppSetController.last();
}

public void next()
{
    if(AppSetController.getHasNext())
    {
        AppSetController.next();
    }
}

public void prev()
{
    if(AppSetController.getHasPrevious())
    {
        AppSetController.previous();
    }
}

public List<appointment__c> getAppoinments()
{
    return (List<appointment__c>)AppSetController.getRecords();
}

public SelectOption[] getAppoinmentExistingViews(){
    return AppSetController.getListViewOptions();
}

public PageReference resetFilter()
{
    AppSetController = null;
    AppSetController.setPageNumber(1);
    return null;
}}

and this is my visualforce page:
 

<apex:page controller="AppointmentListController" sidebar="false" showHeader="false">

<apex:form id="pageForm">

   <apex:actionStatus id="ajaxStatus" startText="Loading..."  stopText=""/>
    <br/><br/>

 <apex:pageBlock title="Appoinments">
    <apex:pageBlockButtons >
            <apex:commandButton action="{!firstPage}" value="|<<" reRender="AppTable"  status="ajaxStatus" />
            <apex:commandButton action="{!prev}" value="Prev" reRender="AppTable"  status="ajaxStatus" />
            <apex:commandButton action="{!next}" value="Next" reRender="AppTable"  status="ajaxStatus" />
            <apex:commandButton action="{!lastPage}" value=">>|" reRender="AppTable"  status="ajaxStatus" />
        </apex:pageBlockButtons>

     <apex:pageBlockTable value="{!Appoinments}" var="item" id="AppTable">
         <apex:column value="{!item.name}" headerValue="Appoinment Name"/>
         <apex:column value="{!item.Status__c}" headerValue="Status"/>
         <apex:column value="{!item.contact}" headerValue="Contact"/>

     </apex:pageBlockTable> 
 </apex:pageBlock>
</apex:form>
</apex:page>

When I add this page to the community,I am getting the error "Error: Error occurred while loading a Visualforce page." What am I doing wrong here?