Protect backend from a few late calls after engine close request

Signed-off-by: falkTX <falktx@falktx.com>

source/backend/CarlaStandalone.cpp

@@ -972,11 +972,15 @@ bool carla_patchbay_disconnect(CarlaHostHandle handle, bool external, uint conne
 
 bool carla_patchbay_set_group_pos(CarlaHostHandle handle, bool external, uint groupId, int x1, int y1, int x2, int y2)
 {
-    CARLA_SAFE_ASSERT_WITH_LAST_ERROR_RETURN(handle->engine != nullptr, "Engine is not initialized", false);
+    CARLA_SAFE_ASSERT_WITH_LAST_ERROR_RETURN(handle->engine != nullptr && handle->engine->isRunning(),
+                                             "Engine is not running", false);
 
     carla_debug("carla_patchbay_set_group_pos(%p, %s, %u, %i, %i, %i, %i)",
                 handle, bool2str(external), groupId, x1, y1, x2, y2);
 
+    if (handle->engine->isAboutToClose())
+        return true;
+
     return handle->engine->patchbaySetGroupPos(false, true, external, groupId, x1, y1, x2, y2);
 }
 
@@ -1877,13 +1881,16 @@ const CarlaInlineDisplayImageSurface* carla_render_inline_display(CarlaHostHandl
                                                                   uint pluginId,
                                                                   uint32_t width, uint32_t height)
 {
-    CARLA_SAFE_ASSERT_RETURN(handle->engine != nullptr, nullptr);
+    CARLA_SAFE_ASSERT_RETURN(handle->engine != nullptr && handle->engine->isRunning(), nullptr);
 
     CarlaPlugin* const plugin = handle->engine->getPlugin(pluginId);
     CARLA_SAFE_ASSERT_RETURN(plugin != nullptr, nullptr);
 
     carla_debug("carla_render_inline_display(%p, %i, %i, %i)", handle, pluginId, width, height);
 
+    if (handle->engine->isAboutToClose())
+        return nullptr;
+
     switch (plugin->getType())
     {
 #ifndef BUILD_BRIDGE_ALTERNATIVE_ARCH

source/frontend/carla_host.py

@@ -2767,7 +2767,9 @@ def canvasCallback(action, value1, value2, valueStr):
         gCarla.gui.updateMiniCanvasLater()
 
     elif action == patchcanvas.ACTION_GROUP_POSITION:
-        if gCarla.gui.fIsProjectLoading or not host.is_engine_running():
+        if gCarla.gui.fIsProjectLoading:
+            return
+        if not host.is_engine_running():
             return
         groupId = value1
         x1, y1, x2, y2 = tuple(int(i) for i in valueStr.split(":"))
@@ -2838,8 +2840,10 @@ def canvasCallback(action, value1, value2, valueStr):
         gCarla.gui.slot_showPluginActionsMenu()
 
     elif action == patchcanvas.ACTION_INLINE_DISPLAY:
-        # FIXME
-        if gCarla.gui.fPluginCount == 0: return
+        if gCarla.gui.fIsProjectLoading:
+            return
+        if not host.is_engine_running():
+            return
         pluginId = value1
         width, height = [int(v) for v in valueStr.split(":")]
         return host.render_inline_display(pluginId, width, height)