fix: improve CSV path handling and error handling in substrait example

[SanjayUG]

Fix: Improve CSV Path Handling and Error Handling in Substrait Example

Which issue does this PR close?

• Closes CSV file path handling in substrait.py example #1053

Rationale for this change

This update improves the CSV path handling and error handling in the Substrait example. The changes ensure cross-platform compatibility and provide more comprehensive error handling, making the code more robust and user-friendly.

What changes are included in this PR?

• fix: Improve CSV path handling and error handling in Substrait example
  • Add cross-platform path handling using os.path
  • Add comprehensive error handling for CSV registration
  • Improve error messages and code organization

Are these changes tested?

Yes, the changes have been tested to ensure that the CSV path handling works correctly across different platforms and that the error handling provides meaningful messages.

Are there any user-facing changes?

No, there are no user-facing changes as this update is related to internal code improvements.

Are there any breaking changes to public APIs?

No, there are no breaking changes to public APIs.

[renato2099]

I am not super familiar with datafusion-python code patterns, but I do like having the exception handling already "documenting the code" 👍

I am no committer, just another open-source enthusiast, but the the PR looks good to me :)

[renato2099]

maybe @timsaucer could do the final approval?

[timsaucer]

I don't think these changes make a substantive difference to the example. One of the main goals of the examples to be as simple and clear as possible for new users to understand the basic API usage. Error trapping is a good and useful practice but this looks like it detracts from the core intent of the example.

If we are going to add it in, then a single try/except block would be my recommended approach rather than these detailed messages for every step of the process. I haven't reviewed each of the stages in these calls to see if it's possible to throw exceptions at every stage, either.

I'll add a note to the original issue report asking for clarity of what they think is the bug.