Correctly rethrow exceptions and improve error messages.

Libs/PluginFramework/ctkDefaultApplicationLauncher.cpp

@@ -88,7 +88,7 @@ QVariant ctkDefaultApplicationLauncher::start(const QVariant& defaultContext)
     {
       if (!relaunch || (context->getPlugin()->getState() != ctkPlugin::ACTIVE))
       {
-        throw e;
+        throw;
       }
       qWarning() << "Application error:" << e.what();
     }

Libs/PluginFramework/ctkPluginFrameworkLauncher.cpp

@@ -460,10 +460,15 @@ QVariant ctkPluginFrameworkLauncher::run(const QVariant& argument)
     }
     return d->appLauncher->reStart(argument);
   }
+  catch (const ctkException& e)
+  {
+    qWarning() << "Application launch failed:" << e.printStackTrace();
+    throw;
+  }
   catch (const std::exception& e)
   {
     qWarning() << "Application launch failed:" << e.what();
-    throw e;
+    throw;
   }
 }