catch and handle exceptions when attempting to complete human tasks (#380)

* catch and handle exceptions when attempting to complete human tasks w/ burnettk

* fix lint

---------

Co-authored-by: jasquat <jasquat@users.noreply.github.com>
Co-authored-by: burnettk <burnettk@users.noreply.github.com>

spiffworkflow-backend/src/spiffworkflow_backend/routes/process_instance_events_controller.py

@@ -138,4 +138,17 @@ def error_detail_show(
                 status_code=400,
             )
         )
-    return make_response(jsonify(process_instance_event.error_details[0]), 200)
+    if len(process_instance_event.error_details) < 1:
+        raise (
+            ApiError(
+                error_code="process_instance_event_error_details_not_found",
+                message=(
+                    f"Error details for process instance event could not be found: {process_instance_event_id}. "
+                    "Perhaps no exception was available."
+                ),
+                status_code=400,
+            )
+        )
+
+    error_details = process_instance_event.error_details[0]
+    return make_response(jsonify(error_details), 200)

spiffworkflow-backend/src/spiffworkflow_backend/routes/tasks_controller.py

@@ -602,7 +602,7 @@ def task_save_draft(
             error_code="process_instance_not_runnable",
             message=(
                 f"Process Instance ({process_instance.id}) has status "
-                f"{process_instance.status} which does not allow tasks to be submitted."
+                f"{process_instance.status} which does not allow draft data to be saved."
             ),
             status_code=400,
         )

spiffworkflow-backend/src/spiffworkflow_backend/services/process_instance_processor.py

@@ -1541,7 +1541,14 @@ class ProcessInstanceProcessor:
             )
 
         task_model.start_in_seconds = time.time()
-        self.bpmn_process_instance.run_task_from_id(spiff_task.id)
+        task_exception = None
+        task_event = ProcessInstanceEventType.task_completed.value
+        try:
+            self.bpmn_process_instance.run_task_from_id(spiff_task.id)
+        except Exception as ex:
+            task_exception = ex
+            task_event = ProcessInstanceEventType.task_failed.value
+
         task_model.end_in_seconds = time.time()
 
         human_task.completed_by_user_id = user.id
@@ -1559,9 +1566,10 @@ class ProcessInstanceProcessor:
 
         ProcessInstanceTmpService.add_event_to_process_instance(
             self.process_instance_model,
-            ProcessInstanceEventType.task_completed.value,
+            task_event,
             task_guid=task_model.guid,
             user_id=user.id,
+            exception=task_exception,
         )
 
         # children of a multi-instance task has the attribute "triggered" set to True
@@ -1577,6 +1585,9 @@ class ProcessInstanceProcessor:
         # this is the thing that actually commits the db transaction (on behalf of the other updates above as well)
         self.save()
 
+        if task_exception is not None:
+            raise task_exception
+
     def get_data(self) -> dict[str, Any]:
         return self.bpmn_process_instance.data  # type: ignore
 

spiffworkflow-backend/src/spiffworkflow_backend/services/process_instance_service.py

@@ -25,6 +25,7 @@ from spiffworkflow_backend.models.process_model_cycle import ProcessModelCycleMo
 from spiffworkflow_backend.models.task import Task
 from spiffworkflow_backend.models.user import UserModel
 from spiffworkflow_backend.services.authorization_service import AuthorizationService
+from spiffworkflow_backend.services.authorization_service import HumanTaskAlreadyCompletedError
 from spiffworkflow_backend.services.authorization_service import HumanTaskNotFoundError
 from spiffworkflow_backend.services.authorization_service import UserDoesNotHaveAccessToTaskError
 from spiffworkflow_backend.services.git_service import GitCommandError
@@ -524,6 +525,8 @@ class ProcessInstanceService:
                 processor.process_instance_model.id, str(spiff_task.id), g.user
             )
             can_complete = True
+        except HumanTaskAlreadyCompletedError:
+            can_complete = False
         except HumanTaskNotFoundError:
             can_complete = False
         except UserDoesNotHaveAccessToTaskError: