#882 Surface subtask errors instead of confusing TypeError in flyte.map Pull request opened by pingsutw Summary • When

flyte.map

returns exceptions as values (

return_exceptions=True

), user code that performs arithmetic on them (e.g.

sum(results)

) would get a confusing

TypeError: unsupported operand type(s) for +: 'int' and 'RetriesExhaustedError'

• Added numeric dunder methods (

__add__

,

__radd__

,

__sub__

,

__mul__

,

__truediv__

,

__floordiv__

and reverses) to

BaseRuntimeError

that re-raise the original subtask error instead Before: Screenshot 2026-03-31 at 12 21 27 AM After: Screenshot 2026-03-31 at 12 21 15 AM Test plan • Unit tests for all arithmetic dunder methods on

BaseRuntimeError

• Integration test:

flyte.map

with failing subtasks →

sum(results)

now surfaces the subtask error • Existing

test_mapping.py

and

test_map_concurrency.py

tests pass (19 total) flyteorg/flyte-sdk