fix: Pipeline.upsert() TypeError with dict role_arn (demo 1773871633) (#77777)

[aviruthen]

Description

Validate role_arn type in Pipeline methods

Problem

When a non-string value (e.g., a dict) is passed as role_arn, the invalid value propagates deep into the call stack before failing with an unhelpful TypeError.

Solution

Added _validate_role_arn() helper that checks role_arn is either None or a string, raising a descriptive ValueError otherwise.

Related Issue

Fixes #77777

Changes Made

• src/sagemaker/workflow/pipeline.py
• tests/unit/sagemaker/workflow/test_pipeline_role_validation_1773871633.py

AI-Generated PR

This PR was automatically generated by the PySDK Issue Agent.

• Confidence score: 85%
• Classification: bug
• SDK version target: V3

Merge Checklist

• Changes are backward compatible
• Commit message follows prefix: description format
• Unit tests added/updated
• Integration tests added (if applicable)
• Documentation updated (if applicable)