Assertion failed in BlockAccessCipherStream

Hey, i get an assertion failed exception inside the `BlockAccessCipherStream:737` when opening a TransactionDB or OptimisitcTransactionDB:
`assert(fileOffset < dataSize);` with dataSize being 0 and fileOffset being 16.
I use the LZ4 compression and a custom comparator. My RocksDB version is 6.1.1, but it happened for other versions aswell.

### Expected behavior
The database is created succesfully

### Actual behavior
I get an assertion failure

### Steps to reproduce the behavior
```c++
rocksdb::Options options;
options.create_if_missing = true;
options.comparator = &m_internals->m_cmp;
options.compression = rocksdb::CompressionType::kLZ4Compression;
rocksdb::Status status = rocksdb::OptimisticTransactionDB::Open(options, "test.db", &m_internals->m_tdb);
```

If you require to see the comparator i can paste it here aswell, but it's a bit larger