Validator: temporarily add artificial panic when micro block producti…

…on fails

This should be removed once #2751 is fixed.

validator/src/micro.rs

@@ -70,6 +70,8 @@ impl<TValidatorNetwork: ValidatorNetwork + 'static> NextProduceMicroBlockEvent<T
         }
     }
 
+    // TODO Remove this line
+    #[allow(unreachable_code)]
     async fn next(
         self,
     ) -> (
@@ -132,6 +134,11 @@ impl<TValidatorNetwork: ValidatorNetwork + 'static> NextProduceMicroBlockEvent<T
                         "Failed to construct micro block"
                     );
 
+                    // Add an artificial panic here so that it's easier to catch any remaining
+                    // mempool bugs.
+                    // TODO Remove this line and the #[allow(unreachable_code)] annotation on this function.
+                    panic!("Failed to construct micro block");
+
                     // Sleep a bit to allow the task to be cancelled externally if needed.
                     delay = Duration::from_millis(50);
                     continue;