i am not sure that's the case.  see my NATS message log:
<NATS debug message>
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "new user msg"
┌ Info: debug
└   payload = "_process_message 3" 
┌ Info: debug
└   payload = "_process_message 5"
┌ Info: debug
└   payload = "_process_message 6"
┌ Info: debug
└   payload = "_process_message 7"
</NATS debug message>

my NATS receiver report the following for a long time
┌ Info: debug
└   payload = "new user msg"

untill I Ctrl + d so shutdown the process then i got the following report
┌ Info: debug
└   payload = "_process_message 3" 
┌ Info: debug
└   payload = "_process_message 5"
┌ Info: debug
└   payload = "_process_message 6"
┌ Info: debug
└   payload = "_process_message 7"









my point is if _process_message() actually run then this code in _process_message()
"raw_msg = take!(agent.inputChannel)"
should take the new msg message out of agent.inputChannel and there should be only one debug message showing
┌ Info: debug
└   payload = "new user msg"

before reaching error("debug marker")