Debugging wireshark dissector

Question

I am writing my first wireshark dissector. I am writing it in Lua, using this as an example. On the second page it says that I can use functions like critical(), warn(), debug() to help debug the code. However, when I add even the simplest

critical("foo")

wireshark complains that

attempt to call global 'critical' (a nil value)

I can't seem to figure out how to use these utility functions. What am I missing?

UPDATE: In case it is relevant, I am running Wireshark 3.0.0

Answer 1

I made that tutorial.

It looks like the logging functions were removed from Wireshark in 3.0 (release notes):

Lua: the various logging functions (debug, info, message, warn and critical) have been removed. Use the print function instead for debugging purposes.

So use print() instead:

print("foo")