fix(pb): handle going away signals gracefully (#4104)

# Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my feature works
- [ ] New and existing unit tests pass locally with my changes

Author: MasterPtato

engine/packages/pegboard/src/workflows/runner.rs

@@ -402,17 +402,26 @@ async fn handle_stopping(
 			})
 			.await?;
 
-		// Set all remaining actors to lost immediately
+		// Set all remaining actors as going away immediately
 		if !actors.is_empty() {
 			for (actor_id, generation) in &actors {
-				ctx.signal(crate::workflows::actor::GoingAway {
-					generation: *generation,
-					reset_rescheduling: reset_actor_rescheduling,
-				})
-				.to_workflow::<crate::workflows::actor::Workflow>()
-				.tag("actor_id", actor_id)
-				.send()
-				.await?;
+				let res = ctx
+					.signal(crate::workflows::actor::GoingAway {
+						generation: *generation,
+						reset_rescheduling: reset_actor_rescheduling,
+					})
+					.to_workflow::<crate::workflows::actor::Workflow>()
+					.tag("actor_id", actor_id)
+					.graceful_not_found()
+					.send()
+					.await?;
+
+				if res.is_none() {
+					tracing::warn!(
+						?actor_id,
+						"actor workflow not found, likely already stopped"
+					);
+				}
 			}
 		}
 	}

engine/packages/pegboard/src/workflows/runner2.rs

@@ -237,14 +237,23 @@ async fn handle_stopping(
 		// Set all remaining actors as going away immediately
 		if !actors.is_empty() {
 			for (actor_id, generation) in &actors {
-				ctx.signal(crate::workflows::actor::GoingAway {
-					generation: *generation,
-					reset_rescheduling: reset_actor_rescheduling,
-				})
-				.to_workflow::<crate::workflows::actor::Workflow>()
-				.tag("actor_id", actor_id)
-				.send()
-				.await?;
+				let res = ctx
+					.signal(crate::workflows::actor::GoingAway {
+						generation: *generation,
+						reset_rescheduling: reset_actor_rescheduling,
+					})
+					.to_workflow::<crate::workflows::actor::Workflow>()
+					.tag("actor_id", actor_id)
+					.graceful_not_found()
+					.send()
+					.await?;
+
+				if res.is_none() {
+					tracing::warn!(
+						?actor_id,
+						"actor workflow not found, likely already stopped"
+					);
+				}
 			}
 		}
 	}