test: add unit test which causes addition overflow in type size computation

This commit will fail when put before either of the previous two commits.

Author: apoelstra

src/bit_machine/mod.rs

@@ -623,7 +623,6 @@ impl From<JetFailed> for ExecutionError {
 
 #[cfg(test)]
 mod tests {
-    #[cfg(feature = "elements")]
     use super::*;
 
     #[cfg(feature = "elements")]
@@ -710,4 +709,20 @@ mod tests {
         );
         assert_eq!(res.unwrap(), Value::unit());
     }
+
+    #[test]
+    fn crash_regression2() {
+        use crate::node::{CoreConstructible as _, JetConstructible as _};
+
+        type Node = Arc<crate::ConstructNode<crate::jet::Core>>;
+
+        let mut bomb = Node::jet(
+            &crate::types::Context::new(),
+            crate::jet::Core::Ch8, // arbitrary jet with nonzero output size
+        );
+        for _ in 0..100 {
+            bomb = Node::pair(&bomb, &bomb).unwrap();
+        }
+        let _ = bomb.finalize_pruned(&());
+    }
 }