Move the Parslet parse into initialize so that invalid function definition will fail on workflow load

[agrare]

I still need to handle the exception types for other failures, but this is a quick way to raise an exception earlier than runtime for a number of failure types

[miq-bot]

Checked commit https://github.com/agrare/floe/commit/cf2eb015d61bfe21128c03d7d3e5fa3a5c928940 with ruby 3.1.5, rubocop 1.56.3, haml-lint 0.51.0, and yamllint 2 files checked, 0 offenses detected Everything looks fine. :trophy: