* Fix bug in add_conditional_edges when no path_map is provided
When an instance of a callable class is passed as the path arg to
add_conditional_edges but no path_map is provided, get_type_hints(path) is
called, which raises a TypeError (since get_type_hints only accepts a module,
class, method, or function).
This patch fixes the error by trying to get type hints from path.__call__ first,
which should work for instances of callable classes.
Tested: Added a test that raises TypeError without the fix in this patch but
passes with the fix.
* More defensive, additional test
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Co-authored-by: Nuno Campos <nuno@langchain.dev>
