Provide more contextual error message for PyCoder

[ian-Liaozy]

Fixes #36824

Description:
Improve error messages by providing more contextual debugging information. Modify the VarIntCoderImpl class to catch the OverflowError and provide a more informative message.

Fix/Changes::

1. Modified encode_to_stream(self, value, out, nested) in coder_impl.py:

   • Wrapped the call to out.write_var_int64(value) in a try...except OverflowError block.
   • If an OverflowError occurs, a new OverflowError is raised with a message explicitly stating:
     • The value causing the error.
     • That the VarIntCoder is limited to the 64-bit signed integer range.

2. estimate_size(self, value, nested=False) in coder_impl.py:

   • Wrapped the call to get_varint_size(value) in a try...except OverflowError block.
   • If an OverflowError occurs, it means the value is too large to even calculate the varint size, so a more specific OverflowError is raised.

Impact of these Changes:

1. When a Python integer larger than what can be represented by a signed 64-bit integer is passed to a Beam pipeline and a VarIntCoder is used, the user will now get a much clearer error message.
2. The message will immediately point to the size limitation of the coder, making it much easier to debug issues.
3. This improves the user experience by making the error message more actionable and less cryptic.

---

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[gemini-code-assist]

Summary of Changes

Hello @ian-Liaozy, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request improves the robustness and user-friendliness of Apache Beam's Python VarIntCoder by enhancing its error handling. It ensures that when integer values exceed the 64-bit signed integer limit, users receive clear, informative error messages that pinpoint the issue and its constraints, rather than cryptic OverflowError exceptions. This change makes it easier for developers to understand and resolve data type limitations within their pipelines.

Highlights

• Enhanced Error Messages: The VarIntCoderImpl now provides more contextual and actionable error messages when an OverflowError occurs during encoding or size estimation. The new messages explicitly state the problematic integer value and clarify that the coder is limited to 64-bit signed integers.
• Improved Debugging Experience: By catching OverflowError in both encode_to_stream and estimate_size methods, the system now guides users directly to the cause of the error (value exceeding 64-bit signed integer range), significantly reducing debugging time for issues related to large integer values in Beam pipelines.

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[ian-Liaozy]

Question: I didn't existing tests code for coder_impl.py, should I add the test code or it is fine?

[ian-Liaozy]

assign set of reviewers

[github-actions]

Assigning reviewers:

R: @jrmccluskey for label python.

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[jrmccluskey]

LGTM, just needs the linting failure fixed.

[ian-Liaozy]

Hi @jrmccluskey, all tests pass now.

[jrmccluskey]

LGTM