diff --git a/.bintray.js b/.bintray.js
index bc48825..c7ae359 100644
--- a/.bintray.js
+++ b/.bintray.js
@@ -8,7 +8,7 @@
     },
 
     "version": {
-        "name": "0.4"
+        "name": "0.5"
     },
 
     "files":
diff --git a/roboschool/cpp-household/render-simple.cpp b/roboschool/cpp-household/render-simple.cpp
index e30970d..265c17a 100644
--- a/roboschool/cpp-household/render-simple.cpp
+++ b/roboschool/cpp-household/render-simple.cpp
@@ -337,32 +337,40 @@ Texture::Texture()  {
     glFuncs->glGenTextures(1, &handle);
 }
 Texture::~Texture()  {
-    QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
-    glFuncs->glDeleteTextures(1, &handle);
+	if(QOpenGLContext::currentContext()!=null){
+		QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
+		glFuncs->glDeleteTextures(1, &handle);
+	}
 }
 Framebuffer::Framebuffer()  {
     QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
     glFuncs->glGenFramebuffers(1, &handle);
 }
 Framebuffer::~Framebuffer()  {
-    QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
-    glFuncs->glDeleteFramebuffers(1, &handle);
+	if(QOpenGLContext::currentContext()!=null){
+		QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
+		glFuncs->glDeleteFramebuffers(1, &handle);
+	}
 }
 Buffer::Buffer()  {
     QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
     glFuncs->glGenBuffers(1, &handle);
 }
 Buffer::~Buffer()  {
-    QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
-    glFuncs->glDeleteBuffers(1, &handle);
+	if(QOpenGLContext::currentContext()!=null){
+		QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
+		glFuncs->glDeleteBuffers(1, &handle);
+	}
 }
 VAO::VAO()  {
     QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
     glFuncs->glGenVertexArrays(1, &handle);
 }
 VAO::~VAO()  {
-    QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
-    glFuncs->glDeleteVertexArrays(1, &handle);
+	if(QOpenGLContext::currentContext()!=null){
+		QOpenGLExtraFunctions *glFuncs = QOpenGLContext::currentContext()->extraFunctions();
+		glFuncs->glDeleteVertexArrays(1, &handle);
+	}
 }
 
 void ContextViewport::_render_single_object(const shared_ptr<Household::ShapeDetailLevels>& m, uint32_t options, int detail, const QMatrix4x4& at_pos)