Spawn main is permitted to return a straight state

os2.rkt

@@ -476,13 +476,18 @@
     (match-define (endpoint (eid pid _) _ (handlers _ _ message-handler)) e)
     (run-trapk state pid message-handler message-topic body)))
 
+(define (maybe-transition->transition t)
+  (cond [(transition? t) t]
+	[else (transition t '())]))
+
 (define (do-spawn spawning-pid main k debug-name state)
   (define new-pid (vm-next-process-id state))
   (define new-name (or debug-name new-pid))
   (match-define (transition initial-state initial-actions)
-    (cond
-     [(procedure? main) (send-to-user (lambda (e) (transition #f (kill #f e))) main new-pid)]
-     [(transition? main) main]))
+    (maybe-transition->transition
+     (cond
+      [(procedure? main) (send-to-user (lambda (e) (transition #f (kill #f e))) main new-pid)]
+      [(transition? main) main])))
   (define initial-process (process new-name new-pid initial-state (set) (set)))
   (define spawned-state
     (struct-copy vm (enqueue-actions state new-pid initial-actions)
@@ -531,10 +536,6 @@
 	(run-ready state pid (apply send-to-user failure-proc trap-k args)))
       state))
 
-(define (maybe-transition->transition t)
-  (cond [(transition? t) t]
-	[else (transition t '())]))
-
 (define (run-ready state pid interrupt-k)
   (define old-state (process-state (hash-ref (vm-processes state) pid)))
   (match-define (transition new-state actions)