Missing error location for constraint

[mzagozen]

Acton Version

0.24.1.20250129.8.25.26

Steps to Reproduce and Observed Behavior

class Foo(object):
    thing: ?bool

    def __init__(self, thing):
        self.thing = thing

mut def remove_thing(foos):
    for f in foos:
        f.thing = None

def process():
    p = []
    foos = [Foo(True)]
    # This is obviously wrong, remove_thing() does not return Iterable
    p.extend(remove_thing(foos))

[error]: Constraint violation
     ╭──▶ @0:0-0:0
     │
   0 │ <no line>
     •
     • ╰╸ None must be a subclass of __builtin__.list[_]
─────╯

Expected Behavior

Error points to somewhere in the line p.extend(remove_thing(foos))