(PHP) Undefined Index from existing keys in getMulti result

$couchbase = new Couchbase(COUCHBASE_HOST . ':' . COUCHBASE_PORT);
$queryKeys = array('testKey', 'testKey1');
// Delete all the keys and then give them some values
foreach ($queryKeys as $currKey) {
    $couchbase->delete($currKey);
    $couchbase->set($currKey, 'testVal ' . $currKey);
}
 
$multiResult = $GLOBALS['membase']->getMulti($queryKeys);
print_r($multiResult); // Shows correct result array
print "\n\n";
 
// Go through the results
foreach ($multiResult as $resultKey => $resultValue) {
    print "result key: $resultKey ; result value: $resultValue \n";
    var_dump($resultKey);
    print "multiResult[$resultKey]: ";
    var_dump(@$multiResult[$resultKey]); // Undefined index error without @
 
    print "\n";
}
 
print "\n\n------\n\n";
 
// Go through the keys that we queried couchbase with
foreach ($queryKeys as $currKey) {
    print "query key: $currKey \n";
    var_dump($currKey);
    var_dump(@$multiResult[$currKey]); // Undefined index error without @
}