Crash due opening bam file

Steps to reproduce:

1. Open _common_data/scenarios/assembly/example-alignment.bam
Expected state importer dialog opens

2. Click "Import"
!! UGENE crashes

Notes:

QList<Task*> BAMImporterTask::onSubTaskFinished(Task* subTask) {
    // ...
    } else if (convertTask == subTask) {
        loadDocTask = LoadDocumentTask::getDefaultLoadDocTask(convertTask->getDestinationUrl());
        res << loadDocTask;
    } 
    // ...
    return res;
}

For some reason ugenedb format not recognized and LoadDocumentTask::getDefaultLoadDocTask(convertTask->getDestinationUrl()) will return NULL task, that triggers assert in TaskScheduler.