fix: Add __str__ and __repr__ methods to ServerError (#489)

Add `__str__` and `__repr__` methods to `ServerError` and fix the misleading comment in the constructor

Author: aneeshgarg

src/a2a/utils/errors.py

@@ -66,6 +66,17 @@ def __init__(
 
  Args:
  error: The specific A2A or JSON-RPC error model instance.
- If None, an `InternalError` will be used when formatting the response.
  """
  self.error = error
+
+ def __str__(self) -> str:
+ """Returns a readable representation of the internal Pydantic error."""
+ if self.error is None:
+ return 'None'
+ if self.error.message is None:
+ return self.error.__class__.__name__
+ return self.error.message
+
+ def __repr__(self) -> str:
+ """Returns an unambiguous representation for developers showing how the ServerError was constructed with the internal Pydantic error."""
+ return f'{self.__class__.__name__}({self.error!r})'