in unified logging, there are 2 predefined LogOutputs:
LogStdoutOutput* LogConfiguration::StdoutLog = nullptr;
LogStderrOutput* LogConfiguration::StderrLog = nullptr;

They are initialized in LogConfiguration::initialize(). Once VM is set up, they are ready. LogConfiguration::parse_log_arguments() still need to go through normalization when outputstr is "stdout" or "stderr".

It needs to allocate a tiny buffer (12 bytes) on C_HEAP and jio_snprintf(). it's risky and may return false.

I think we can specify idx = 0 for stdout and 1 for stderr.
It's worth noting that it's impossible to delete outputs[0] and [1]. check the assertion of LogConfiguration::delete_output(size_t idx)