Connect to streams via uv

I am trying to connect our frontend to Julia via the provided uv streams (JL_STOUT,…). The goal is to receive all outputs and show them in our own terminal. However when calling uv_is_readable it returns 0. Also uv_read_start returns 0 when connecting to the streams. But when Julia is generating output the callbacks are called and I also receive the right buffers. But it feels wrong to ignore the return values. Do I might miss something?