assertion failed: `self.contains_function(function_name)`

[tim-hoffman]

Reproduced by circom/tests/circom_doc_examples/04.circom.
It tries to lookup AND as a function but it's a template. Stack trace shows this happens in DeclarationInfo::from_template() which means information about all templates has not yet been collected and thus the confusion. Near the top of the stack, it's trying to generate a poly.expr for a dimension expression when it encounters the AND() call and tries to generate it as a function call.

[tim-hoffman]

Per #411 it now produces a Function not found: error instead of an assertion failure.