private function getProcessOutput(): ProcessOutputInterface
    {
        if (is_null($this->output)) {
            $this->output = new ProcessOutput($this->exitCode, $this->fullStdOut, $this->fullStdErr);
            $this->observer->processExited($this->pid, $this->output);
        }

        return $this->output;
    }
private function getProcessOutput(): ProcessOutputInterface
    {
        if (is_null($this->output)) {
            $this->output = new ProcessOutput($this->exitCode, $this->fullStdOut, $this->fullStdErr);
            $this->observer->processExited($this->pid, $this->output);
        }

        return $this->output;
    }
Returns the output of the process (exit code, stdout & stderr).