[data] Bad error message when function outputs cannot be pickled about ray

[Oblynx]

Struggling a lot with Ray serialization, I feel that the proposed error message is still not clear enough, because it doesn't refer to the user code that sources the offending object.

Is it possible with some extra inspection to come up with an error message like the following?

This is the log of the execution plan, indicating the user functions by name:

Execution plan of Dataset: InputDataBuffer[Input] -> TaskPoolMapOperator[MapBatches(read_dataset)] -> TaskPoolMapOperator[Map(merge_components)->Map(remesh_surface)]

The error message refers to one of the user defined functions:

                                                                +                 + +
Checking Serializability of <ray.data._internal.... TaskPoolMapOperator.Map(remesh_surface) object at 0x16fffa040>
================================================================================
#  list of objects that pass serialization check ...
!!! FAIL serialization: cannot pickle 'socket' object