Expression.full() errors if any Expressions inside it

[machow]

Describe the bug

For griffe v0.28.1, when Expression.full() gets called, if it contains any expressions within it, then it attempts to call .canonical on them, which produces an AttributeError:

AttributeError: 'Expression' object has no attribute 'canonical'

Here's an example that I used to check against:

a: Union[list[str], str]

[pawamoy]

Damn, how am I not detecting this with the tests suite yet. Thanks for the report, will fix asap

[machow]

No worries! I was able to make a quick fix and can submit a PR in a sec! (No worries if you end up fixing another way)