Add raise_cannot_infer_root_key_error to config

[tashirosota]

Purpose

• Raise error when cannot infer root key by v10.0.7 . I think this is braking change.
• Added config that you can upgrade without changing existing code.

Changes

• ArgumentError changes to CannotInferRootKeyError in CollectionSerializer#json_key
  • Custom error helps clarify the problem
• Add config.raise_cannot_infer_root_key_error
• Add test when serializer does not have type and collection is empty

Related GitHub issues

• Raise ArgumentError "Cannot infer root key from collection type. Please specify the root or each_serializer option, or render a JSON String" when collection is empty array in >= 10.0.7 #2406

Our project has many like this code😢

::ActiveModelSerializers::SerializableResource.new(
  collections, # [] empty array
  each_serializer: NonTypeCollectionSerializer,
).serializable_hash || []
※ v0.10.6

[wasifhossain]

Looks good to me

[tashirosota]

@wasifhossain
Will this PR be merged?

[wasifhossain]

let's do this

[wasifhossain]

thanks for the reminder!

[mvz]

This doesn't seem to resolve the problem that this error is also raised when each_serializer is specified, even though specifying an each_serializer is suggested as a way to resolve the error.

[tashirosota]

@mvz
When each_serializer is specified and don't want to make an error.
Can set ActiveModelSerializers.config.raise_cannot_infer_root_key_error =false and not raise error.
This error coused when each_serializer is specified and (serializer's type is null || collection is empty || root key is null), it is correct behavior, but braking change.
So I patched this option, resolve to this case < v0.10.6

::ActiveModelSerializers::SerializableResource.new(
  collections, # [] empty array
  each_serializer: NonTypeCollectionSerializer,
).serializable_hash || []