I love Alfred but I struggled at first to troubleshoot my workflow scripts due to difficulty finding a way to debug. I've seen posts mentioning writing logs to an external file but that seemed hack-y, especially since Alfred includes a debug console. If you'd like to use the console to debug your scripts, I found the following very useful. It would be great if there were a mention of this in the docs:
To show script output in the debug console, print (or echo or put, etc) the output to stderr instead of stdout.
In a Bash script:
>&2 echo "Log this output to the console"
In a Python script:
sys.stderr.write("Log this to the console")
For other languages, look for an equivalent method that allows you to log to stderr.