In our current logic, index page will be pre-decoded but it will return OK
as index page use BinaryPlainPageBuilder and first 4 bytes of the page is a offset
so it's high probablility not equal to EncodingTypePB::DICT_ENCODING which
is 5.
Code in bitshuffle_page_pre_decode.h
```
if constexpr (USED_IN_DICT_ENCODING) {
auto type = decode_fixed32_le((const uint8_t*)&data.data[0]);
if (static_cast<EncodingTypePB>(type) != EncodingTypePB::DICT_ENCODING) {
return Status::OK();
}
size_of_dict_header = BINARY_DICT_PAGE_HEADER_SIZE;
data.remove_prefix(4);
}
```
But if type just equal to EncodingTypePB::DICT_ENCODING and then it will use
BitShuffle to decode BinaryPlainPage, which will leads to an fatal error.
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