Inputs that are just deltas without an uncompressed byte can lead to a bit shift that is higher than 64 for a long on this line. This is undefined behavior, but it is gracefully handled by the decompressor currently (an error is raised in the materializer), so no errors are occurring in production. However, the bson_column_validate_fuzzer is crashing. We should fix this issue explicitly.  The full output of the fuzzer is in the comments.