If the key does not exist in the store, an exception is thrown.
Any integer or string value is accepted as key. If any other type is
passed for the key, an {@link InvalidKeyException} is thrown. You should
make sure that you only pass valid keys to the store.
If the backend of the store cannot be read, a {@link ReadException}
is thrown. You should always handle this exception in your code:
php
try {
$value = $store->getOrFail($key);
} catch (ReadException $e) {
read failed
}