Positional is more threadsafe, since the global seek position is not affected, but when such syscalls are not available, preemptively initializing in streaming mode skips a failed syscall.
See also:
readerpub fn readerStreaming(file: File, io: Io, buffer: []u8) Reader
pub fn readerStreaming(file: File, io: Io, buffer: []u8) Reader {
return .initStreaming(file, io, buffer);
}