Changing default resolver to dict don't work well with Union types

[Syndorik]

Describe the Bug

Trying to change the default resolver to getitem do not work with union types.

System Information

• Operating system: Ubuntu
• Strawberry version (if applicable): Strawberry graphql playground

Additional Context

You can find in the link a way to duplicate the bug!
https://play.strawberry.rocks/?gist=45898fde459d7626b3879292177eecb6

This comes from a discord discussion that was here : https://discord.com/channels/689806334337482765/1221835876448079902

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[Syndorik]

From examining source code, the get_type_resolver method of StrawberryUnion object checks the type name and see if it's in the schema. When you change the default resolver, you work with objects that are not strawberry types making this function throwing error.

I guess a work around would be to have named dict somehow, or precise a typename inside the structure used!