Exceptions when accessing undefined values in Bridged Dicts

[adamlwgriffiths]

I'm trying to implement functionality in the Router beyond just the routes property.

Specifically, the beforeEach function.

Using the router example from the documentation, I modify it like so:

router = Router()

def before_each(to_, from_, next):
    print(f'before_each({to_}, {from_}, {next})')
    print(f'type(to_) = {type(to_)}')
    print(f'type(from_) = {type(from_)}')
    print(f'to_.keys() = {to_.keys()}')
    print(f'to_.values() = {to_.values()}')
    print(f'to_.items() = {to_.items()}')
    next()

router.beforeEach(pyjs_bridge(before_each))

The output of this is:

before_each([object Window], [object Window], <function >)

brython.min.js:1 type(to_) = <class 'vue.bridge.dict.Dict'>

brython.min.js:1 type(from_) = <class 'vue.bridge.dict.Dict'>

brython.min.js:1 to_.keys() = ('name', 'meta', 'path', 'hash', 'query', 'params', 'fullPath', 'matched')

vue-router.js:22 [vue-router] uncaught error during route navigation:

vue-router.js:2322 name
    at Object._b_.AttributeError.$factory (eval at $B.$make_exc (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:327985), <anonymous>:3:15)
    at Object.$B.attr_error (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:330533)
    at $B.JSObj.__getattribute__ (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:402240)
    at Object.$B.$getattr (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:273895)
    at getattr (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:267994)
    at __getitem__497 (eval at run_py (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:414511), <anonymous>:251:99)
    at Object.$B.$getitem (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:221124)
    at eval (eval at run_py (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:414511), <anonymous>:878:11)
    at Generator.next (<anonymous>)
    at Object.$B.generator.send (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:643756)

vue-router.js:2286 Uncaught (in promise) name
    at Object._b_.AttributeError.$factory (eval at $B.$make_exc (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:327985), <anonymous>:3:15)
    at Object.$B.attr_error (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:330533)
    at $B.JSObj.__getattribute__ (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:402240)
    at Object.$B.$getattr (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:273895)
    at getattr (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:267994)
    at __getitem__497 (eval at run_py (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:414511), <anonymous>:251:99)
    at Object.$B.$getitem (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:221124)
    at eval (eval at run_py (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:414511), <anonymous>:878:11)
    at Generator.next (<anonymous>)
    at Object.$B.generator.send (https://cdn.jsdelivr.net/npm/brython@3.10.6/brython.min.js:1:643756)

As you can see, any attempt to access the values (it seems to be specifically the 'name' value in this case) causes issues.

However, I am able to get out the values the VueRoute actually defined.
Ie. using:

    print(f'to_["path"] = {to_["path"]}')
    print(f'to_.get("component") = {to_.get("component")}')

Doesn't cause an exception and does lead to output

to_["path"] = /page1

to_.get("component") = None