err_desc() = invalid_attributes
| invalid_exports
| {arg_mismatch, fa()}
| {bittype_unit, fa()}
| {illegal_expr, fa()}
| {illegal_guard, fa()}
| {illegal_pattern, fa()}
| {illegal_try, fa()}
| {not_bs_pattern, fa()}
| {not_pattern, fa()}
| {not_var, fa()}
| {pattern_mismatch, fa()}
| {return_mismatch, fa()}
| {undefined_function, fa()}
| {duplicate_var, cerl:var_name(), fa()}
| {unbound_var, cerl:var_name(), fa()}
| {undefined_function, fa(), fa()}
| {tail_segment_not_at_end, fa()}
fa() = {atom(), arity()}
warning() = {module(), term()}