This issue was found by Coverity. The RleDecoder::NextCounts method has the following code to fetch the repeated literal in repeated runs:
Coverity says this:
Pointer "&this->current_value_" points to an object whose effective type is "unsigned long long" (64 bits, unsigned) but is dereferenced as a narrower "unsigned int" (32 bits, unsigned). This may lead to unexpected results depending on machine endianness.
In addition, it's not obvious whether current_value_ also needs byte-swapping (presumably, at least in the Parquet file format, it's supposed to be stored in little-endian format in the RLE bitstream).