Rework joiner_token unhandled stopreason handling

src/errors.rs

@@ -141,5 +141,18 @@ pub(crate) fn handle_dropped_error<ErrType: ErrTypeTraits>(
     }
 }
 
+// This function contains code that stems from the principle
+// of defensive coding - meaning, handle potential errors
+// gracefully, even if they should not happen.
+// Therefore it is in this special function, so we don't
+// get coverage problems.
+pub(crate) fn handle_unhandled_stopreason<ErrType: ErrTypeTraits>(
+    maybe_stop_reason: Option<SubsystemError<ErrType>>,
+) {
+    if let Some(stop_reason) = maybe_stop_reason {
+        tracing::warn!("Unhandled stop reason: {:?}", stop_reason);
+    }
+}
+
 #[cfg(test)]
 mod tests;

src/errors/tests.rs

@@ -88,3 +88,13 @@ fn handle_dropped_errors() {
 
     assert!(logs_contain("An error got dropped: \"ABC\""));
 }
+
+#[test]
+#[traced_test]
+fn handle_unhandled_stopreasons() {
+    handle_unhandled_stopreason(Some(SubsystemError::<BoxedError>::Panicked(Arc::from(
+        "def",
+    ))));
+
+    assert!(logs_contain("Unhandled stop reason: Panicked(\"def\")"));
+}

src/utils/joiner_token.rs

@@ -2,7 +2,10 @@ use std::{fmt::Debug, sync::Arc};
 
 use tokio::sync::watch;
 
-use crate::{errors::SubsystemError, ErrTypeTraits};
+use crate::{
+    errors::{handle_unhandled_stopreason, SubsystemError},
+    ErrTypeTraits,
+};
 
 struct Inner<ErrType: ErrTypeTraits> {
     counter: watch::Sender<(bool, u32)>,
@@ -126,9 +129,7 @@ impl<ErrType: ErrTypeTraits> JoinerToken<ErrType> {
             maybe_parent = parent.parent.as_ref();
         }
 
-        if let Some(stop_reason) = maybe_stop_reason {
-            tracing::warn!("Unhandled stop reason: {:?}", stop_reason);
-        }
+        handle_unhandled_stopreason(maybe_stop_reason);
     }
 
     pub(crate) fn downgrade(self) -> JoinerTokenRef {