Accommodate custom components in maybe_raise_or_warn

[neo]

What does this PR do?

by using get_class_obj_and_candidates, this now can also check against custom components being passed in and not error out as not found.

side note

I also noticed the second argument library from maybe_raise_or_warn isn't being used, and we might want to remove it if we don't plan to use it later?

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• git blame author: @sayakpaul
• General functionalities: @sayakpaul @yiyixuxu @DN6

[sayakpaul]

What is the use case for this?

[neo]

What is the use case for this?

so not only instantiated diffusers components can be passed into a pipeline:

pipe2 = DiffusionPipeline.from_pretrained(..., vae=pipe1.vae)

but also for custom components in the same way:

custom_pipe2 = DiffusionPipeline.from_pretrained(..., custom_component=existing_instance)

[sayakpaul]

What error do we get without this change?

[neo]

What error do we get without this change?

It would raise here because it's not real library but custom component/module

and as you can see from def get_class_obj_and_candidates, it's the same logic but with added condition to get_class_from_dynamic_module — I think it should've used this util from the beginning, maybe the util was added after this piece of code