Merge bitcoin#12374: qt: Make sure splash screen is freed on AppInitM…

…ain fail

1e5d14b qt: Clarify some comments (Wladimir J. van der Laan)
f5a4c3d qt: Make sure splash screen is freed on AppInitMain fail (Wladimir J. van der Laan)

Pull request description:

  The `splashFinished` event was never sent if AppInitMain fails, causing the splash screen to stick around, causing problems later.

  This bug has existed for a while but is now trigging potential crashed because the splash screen subscribes to wallet events.

  Meant to fix bitcoin#12372.

Tree-SHA512: 192a7e3a528015e771d7860dd95fd7b772292fd8064abf2a3cf3a8ea0d375cd43a6e8ed37ca1a38962fe1410c934599e557adf6a8ef9d87ec7f61b6e5fd8db7e

src/qt/dash.cpp

@@ -553,13 +553,14 @@ void BitcoinApplication::initializeResult(bool success)
 #endif
         pollShutdownTimer->start(200);
     } else {
-        quit(); // Exit main loop
+        Q_EMIT splashFinished(window); // Make sure splash screen doesn't stick around during shutdown
+        quit(); // Exit first main loop invocation
     }
 }
 
 void BitcoinApplication::shutdownResult()
 {
-    quit(); // Exit main loop after shutdown finished
+    quit(); // Exit second main loop invocation after shutdown finished
 }
 
 void BitcoinApplication::handleRunawayException(const QString &message)