f - Add debug_asserts for funding_negotiation invariant

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jkczyz

lightning/src/ln/channel.rs

@@ -7250,6 +7250,10 @@ where
 			.pending_splice
 			.as_mut()
 			.expect("reset_pending_splice_state requires pending_splice");
+		debug_assert!(
+			pending_splice.funding_negotiation.is_some(),
+			"reset_pending_splice_state requires an active funding negotiation"
+		);
 		let is_initiator = pending_splice
 			.funding_negotiation
 			.take()
@@ -7296,6 +7300,10 @@ where
 		}
 
 		let pending_splice = self.pending_splice.as_ref()?;
+		debug_assert!(
+			pending_splice.funding_negotiation.is_some(),
+			"maybe_splice_funding_failed requires an active funding negotiation"
+		);
 		let is_initiator = pending_splice
 			.funding_negotiation
 			.as_ref()