Sketch up (still defunct) solution to problem

Author: Felix Schlitter

src/Effect/Aff.js

@@ -475,8 +475,12 @@ var Aff = function () {
               // bracket count is non-zero then we are in a masked state so it's
               // impossible to be killed.
               if (interrupt && interrupt !== tmp && bracketCount === 0) {
-                step = attempt._1.killed(util.fromLeft(interrupt))(attempt._2);
-              } else if (fail) {
+               if (step == null || util.isLeft(step)) {
+                 step = attempt._1.killed(util.fromLeft(interrupt))(attempt._2);
+               } else {
+                 step = attempt._1.completed(util.fromRight(step))(attempt._2);
+               }
+             } else if (fail) {
                 step = attempt._1.failed(util.fromLeft(fail))(attempt._2);
               } else {
                 step = attempt._1.completed(util.fromRight(step))(attempt._2);