fix: GenAI SDK client - Fix typo in error message for optimize_prompt

PiperOrigin-RevId: 792273838

Author: sararob

vertexai/_genai/_prompt_optimizer_utils.py

@@ -15,7 +15,6 @@
 """Utility functions for prompt optimizer."""
 
 import json
-from google.genai import errors
 from . import types
 
 
@@ -65,7 +64,8 @@ def _clean_and_parse_optimized_prompt(output_str: str):
  try:
  return json.loads(cleaned_string)
  except json.JSONDecodeError as e:
- raise errors.ClinentError(
+ # TODO(b/437144880): raise errors.ClientError here instead
+ raise ValueError(
  f"Failed to parse the response from prompt optimizer endpoint. {e}"
  ) from e