Added some assertions to catch event-based objects being used before the message manager has been initialised

modules/juce_events/broadcasters/juce_AsyncUpdater.cpp

@@ -33,10 +33,8 @@ public:
             owner.handleAsyncUpdate();
     }
 
-    Atomic<int> shouldDeliver;
-
-private:
     AsyncUpdater& owner;
+    Atomic<int> shouldDeliver;
 
     JUCE_DECLARE_NON_COPYABLE (AsyncUpdaterMessage)
 };
@@ -53,13 +51,19 @@ AsyncUpdater::~AsyncUpdater()
     // pending on the main event thread - that's pretty dodgy threading, as the callback could
     // happen after this destructor has finished. You should either use a MessageManagerLock while
     // deleting this object, or find some other way to avoid such a race condition.
-    jassert ((! isUpdatePending()) || MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    jassert ((! isUpdatePending())
+              || MessageManager::getInstanceWithoutCreating() == nullptr
+              || MessageManager::getInstanceWithoutCreating()->currentThreadHasLockedMessageManager());
 
     activeMessage->shouldDeliver.set (0);
 }
 
 void AsyncUpdater::triggerAsyncUpdate()
 {
+    // If you're calling this before (or after) the MessageManager is
+    // running, then you're not going to get any callbacks!
+    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+
     if (activeMessage->shouldDeliver.compareAndSetBool (1, 0))
         if (! activeMessage->post())
             cancelPendingUpdate(); // if the message queue fails, this avoids getting

modules/juce_events/timers/juce_Timer.cpp

@@ -294,6 +294,10 @@ Timer::~Timer()
 
 void Timer::startTimer (const int interval) noexcept
 {
+    // If you're calling this before (or after) the MessageManager is
+    // running, then you're not going to get any timer callbacks!
+    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+
     const TimerThread::LockType::ScopedLockType sl (TimerThread::lock);
 
     if (timerPeriodMs == 0)