refactor: raise PipelineError when Pipeline.from_dict receives an invalid type

[tstadel]

Related Issues

• fixes getting cryptic Value error if type '' is passed:
  ValueError: not enough values to unpack (expected 2, got 1)

Proposed Changes:

• raise PipelineError

How did you test it?

• added test

Notes for the reviewer

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 12928155465

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 31 unchanged lines in 1 file lost coverage.
• Overall coverage remained the same at 91.336%

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Files with Coverage Reduction	New Missed Lines	%
core/pipeline/base.py	31	88.64%

Totals
Change from base Build 12927997470:	0.0%
Covered Lines:	8855
Relevant Lines:	9695

---

💛 - Coveralls

[anakin87]

Thanks for the PR...

Do you know when this problem happens? When are we serializing empty types?

Also, what do you think about catching empty strings earlier in the process? It might be helpful to raise a clearer error message. Maybe extend the check here, for instance:
Extend the check here, for example

                if "type" not in component_data:
                    raise PipelineError(f"Missing 'type' in component '{name}'")

[tstadel]

Thanks for the PR...

Do you know when this problem happens? When are we serializing empty types?

Also, what do you think about catching empty strings earlier in the process? It might be helpful to raise a clearer error message. Maybe extend the check here, for instance: Extend the check here, for example

                if "type" not in component_data:
                    raise PipelineError(f"Missing 'type' in component '{name}'")

I think this type of error is a bit exotic, dc's pipeline builder falls back to empty string if a component type is not known. But this can be fixed otherwise. For haystack, there should be just a reasonable error message in that case.

Do you think it's worth the granularity? An empty string is one case where it breaks, a string without "." is another. The proposed solution solves both in very simple way.

[anakin87]

Now I understand better, and I'm OK with this PR.

I only request some minor changes.

[anakin87]

👍