Catching global "@In attribute requires non-null value" in SEAM 2

On PAGE A is a table with some data from the database.
by clicking on a row, the page will be forwarded to PAGE B and in the controller the entity will be injected

@DataModelSelection(value = ENTITY_LIST_NAME)
@Out(value = ENTITY_NAME, scope = ScopeType.CONVERSATION, required = false)
private Entity entity;

this works as it should.

The problem is, that our users seems to use bookmark for PAGE B, so the entity will never be injected because they never visited PAGE A

so they always throw this exception

@In attribute requires non-null value

Is there a global function to catch all @In attribute requires non-null value exceptions and forward the user to PAGE C (startpage)?
(of course i can catch this execption on PAGE B but this happens not only on one page, we want to handle this exception on every page)

we are using: jboss5 + jsf 1.2 + seam 2

UPDATE after the answer of EmirCalabuch:
I also tried the hint from EmirCalabuch with:

<page conversation-required="true" no-conversation-view-id="PageC.xhtml" />

but the problem is, that the conversation is alive at this moment, to this forwarding to pageC never happens...

i also made in the page.xml of this page something like:

<action execute="#{controller.checkIfEntityIsSet()}" />
<navigation>
    <rule if-outcome="HOME">
            <redirect          
             view-id="/pages/home.xhtml"
            />
        </rule>
</navigation>

and in my Controller.java i have somthing like this:

public String checkIfEntityIsSet(){
        if(getEntity() == null){
            return "HOME"; 
        }
        return "";          
    }

but this checkIfEntityIsSet() is never called, because the @In attribute requires non-null value is thrown before... so this was not a help at all...

i managed it now different:

in the Controller.java i have for the initialization something like this:

@Create
public void initialize() throws MissingMyEntityException {

    if(qualifiedCustomer == null){
        throw new MissingMyEntityException("something wrong");
    }
    ....
}

my MissingMyEntityException.java looks like this:

public class MissingMyEntityException extends Exception {

    private static final long serialVersionUID = 8640645441429393157L;

    public MissingMyEntityException(String message) {
        super(message);
    }

}

and in the pages.xml i have the exception handler like this:

<exception class="com.dw.companyName.view.xyz.exception.MissingMyEntityException">
        <redirect view-id="/pages/home.xhtml">
            <message>something went wrong</message>
        </redirect>
    </exception>

and this fixed the problem.
but thanks for your help, but it was not working your way :(