Feature summary:
Functions on Wikifunctions should be able to raise warnings in their execution. A warning consists in an object of type Z5 that, instead of being raised and blocking the execution, is logged in a separate log that collects all the warnings generated by a function call (similarly to how currently the Debug log works).
Use case(s):
Functions could use warnings to signal that something went wrong in a context in which it is better not to completely interrupt the execution. One of the primary applications for this feature would be in Natural Language Generation functions for Abstract Wikipedia: for these functions, it is pretty common to encounter some problem (like missing lexemes, missing information on Wikidata, etc.), and the policy is not to interrupt the execution, but to try to implement a fallback behavior. While this behavior allows to produce a partially correct output even for languages with minor support, it has the drowback that it obscures completely all the issues that the function execution identified and had to circumvent. With warnings, these issues would not be completely lost.
Benefits:
Warnings could be very useful for diagnostics (I am thinking mainly about Abstract Wikipedia), in order to better guide the contributors to the right actions to do in order to improve the output of function calls.
