If a 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 = $store->getMultipleOrFail(array($key1, $key2));
} catch (ReadException $e) {
read failed
}