Error handling - identify which block in which pipeline triggers an exception

[markmc]

See #118 for the background

In general, I think when there is an error with a block, we don't make it easy to know which block in which pipeline caused it

A config_path not found case looks like

  File "/home/markmc/sdg/src/instructlab/sdg/sdg.py", line 19, in generate
    dataset = pipeline.generate(dataset)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/markmc/sdg/src/instructlab/sdg/pipeline.py", line 57, in generate
    block = block_type(self.ctx, **block_config)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/markmc/sdg/src/instructlab/sdg/llmblock.py", line 66, in __init__
    self.block_config = self._load_config(config_path)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/markmc/sdg/src/instructlab/sdg/block.py", line 54, in _load_config
    with open(config_path, "r", encoding="utf-8") as config_file:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/home/markmc/sdg/src/instructlab/sdg/configs/skills/freeform_questions.yaml.foobar'

Which isn't so bad, because you just have to find the block with that path

But in other cases it might not be so easy to identify which block is causing an error - if we catch exceptions and add the pipeline+block name, that would be a big improvement

[gabe-l-hart]

Per a pointer from @russellb, I'm going to take a look at this one today and will report my progress here. I don't have write access to assign to myself though.

[markmc]

In #155, @russellb asked for before/after examples for the fix. What's currently proposed is to catch exceptions from block.generate(), so here's an example of the current behavior:

INFO 2024-07-17 07:08:14,120 pipeline.py:77: generate Running block: gen_questions
INFO 2024-07-17 07:08:14,120 pipeline.py:78: generate Dataset({
    features: ['task_description', 'seed_question', 'seed_response'],
    num_rows: 5
})
...
  File "/home/markmc/sdg/src/instructlab/sdg/sdg.py", line 20, in generate
    dataset = pipeline.generate(dataset)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/markmc/sdg/src/instructlab/sdg/pipeline.py", line 80, in generate
    dataset = block.generate(dataset)
              ^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/markmc/sdg/src/instructlab/sdg/llmblock.py", line 181, in generate
    raise Exception("TEST")
Exception: TEST

This case isn't actually so problematic because the context is logged - Running block: gen_questions