Add a system for backends to handle device lost/OOM errors and report it

* The UI will become non-functional and the backend will be replaced with a do-
  nothing one that keeps things alive without needing error bulletproofing
  everywhere in the real backend.

qrenderdoc/Code/ReplayManager.cpp

@@ -48,6 +48,8 @@ void ReplayManager::OpenCapture(const QString &capturefile, const ReplayOptions
   if(m_Running)
     return;
 
+  m_FatalError = ReplayStatus::Succeeded;
+
   // TODO maybe we could expose this choice to the user?
   int proxyRenderer = -1;
 
@@ -296,6 +298,7 @@ void ReplayManager::CancelReplayLoop()
 void ReplayManager::CloseThread()
 {
   m_Running = false;
+  m_FatalError = ReplayStatus::Succeeded;
 
   m_RenderCondition.wakeAll();
 
@@ -492,6 +495,13 @@ void ReplayManager::run(int proxyRenderer, const QString &capturefile, const Rep
 
       cmd->method(m_Renderer);
 
+      ReplayStatus err = m_Renderer->GetFatalErrorStatus();
+      if(m_FatalError == ReplayStatus::Succeeded && err != ReplayStatus::Succeeded)
+      {
+        m_FatalError = err;
+        m_FatalErrorCallback();
+      }
+
       {
         QMutexLocker lock(&m_TimerLock);
         m_CommandTimer.invalidate();