Don't attempt to open an empty texture

apps/openmw/mwrender/sky.cpp

@@ -1550,12 +1550,14 @@ void SkyManager::setWeather(const WeatherResult& weather)
     {
         mNextClouds = weather.mNextCloudTexture;
 
+        if (!mNextClouds.empty())
+        {
             std::string texture = Misc::ResourceHelpers::correctTexturePath(mNextClouds, mSceneManager->getVFS());
 
-        if (!texture.empty())
             mCloudUpdater2->setTexture(mSceneManager->getTextureManager()->getTexture2D(texture,
                                                                                        osg::Texture::REPEAT, osg::Texture::REPEAT));
         }
+    }
 
     if (mCloudBlendFactor != weather.mCloudBlendFactor)
     {