assume code 1 task 9 is oom

Fixes #750

src/tasks.js

@@ -161,10 +161,18 @@ function startTask(id, options, callback) {
         get(id, function (getError, task) {
             let taskError;
             if (!getError && task.percent !== 100) { // taskworker crashed or was killed by us
-                taskError = {
-                    message: code === 0 ? `Task ${id} ${timedOut ? 'timed out' : 'stopped'}` : `Task ${id} crashed with code ${code} and signal ${signal}`,
-                    code: code === 0 ? (timedOut ? exports.ETIMEOUT : exports.ESTOPPED) : exports.ECRASHED
-                };
+                if (code === 0) {
+                    taskError = {
+                        message: `Task ${id} ${timedOut ? 'timed out' : 'stopped'}` ,
+                        code: timedOut ? exports.ETIMEOUT : exports.ESTOPPED
+                    };
+                } else { // task crashed
+                    taskError = {
+                        message: signal === 9 ? `Task ${id} crashed as it ran out of memory` : `Task ${id} crashed with code ${code} and signal ${signal}`,
+                        code: exports.ECRASHED
+                    };
+                }
+
                 // note that despite the update() here, we should handle the case where the box code was restarted and never got taskworker exit
                 setCompleted(id, { error: taskError }, NOOP_CALLBACK);
             } else if (!getError && task.error) {