Passing an invalid uri to the referrer header should no longer throw

[roelvanduijnhoven]

Due to the change in #147 we removed the try/catch control structures from our code. However: exceptions are still generated. I think that this is not intended.

The only valid way to check for a referrer is now the following. Which is kind of cumbersome:

function isRefererFromGitHub($headers) {
    try {
        $referer = $headers->get('Referer');
        if (!$referer instanceof \Zend\Http\Header\GenericHeader) {
            return false;
        }
        
        return $referer->getUri()->getHost() === 'github.com';
    } catch (\Zend\Http\Header\Exception\InvalidArgumentException $e) {
        return false;
    }
}

This PR fixes this by wrapping the exception generated.

---

I am however a bit unsure if this is correct. The release notes state:

Now, Header::has() will return false for such headers

However; in my case the has function does yield true. Therefore I omitted that assertion from my test code.

Any thoughts @webimpress @weierophinney?

[weierophinney]

This is a case where has() SHOULD return true, but get() MUST raise an exception. As such.

We have a similar situation in zend-servicemanager: an entry can be both registered, allowing has() to return true, but, due to missing dependencies or other problems, get() will raise an exception. This is normal; has() is simply indicating that the container knows about the entry. As such, your changes make sense.

[weierophinney]

Thanks, @roelvanduijnhoven!