add assertIsSetup() and use it from OSThread constructor

fixes nasty bug @mc-hamster discovered with plugin order of operations

src/concurrency/OSThread.h

@@ -17,14 +17,14 @@ extern InterruptableDelay mainDelay;
 
 /**
  * @brief Base threading
- * 
+ *
  * This is a pseudo threading layer that is super easy to port, well suited to our slow network and very ram & power efficient.
  *
  * TODO FIXME @geeksville
  *
  * move more things into OSThreads
  * remove lock/lockguard
- * 
+ *
  * move typedQueue into concurrency
  * remove freertos from typedqueue
  */
@@ -42,7 +42,6 @@ class OSThread : public Thread
     static bool showWaiting;
 
   public:
-
     /// For debug printing only (might be null)
     static const OSThread *currentThread;
 
@@ -71,4 +70,19 @@ class OSThread : public Thread
     virtual void run();
 };
 
+/**
+ * This flag is set **only** when setup() starts, to provide a way for us to check for sloppy static constructor calls.
+ * Call assertIsSetup() to force a crash if someone tries to create an instance too early.
+ *
+ * it is super important to never allocate those object statically.  instead, you should explicitly
+ *  new them at a point where you are guaranteed that other objects that this instance
+ * depends on have already been created.
+ *
+ * in particular, for OSThread that means "all instances must be declared via new() in setup() or later" -
+ * this makes it guaranteed that the global mainController is fully constructed first.
+ */
+extern bool hasBeenSetup;
+
+void assertIsSetup();
+
 } // namespace concurrency