Example has OpenGL errors

[Kipt]

In the example code, the call next to comment
// attach texture to the framebuffer
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D, viewTex, 0);
causes GL_INVALID_OPERATION to be raised. Debug message says:

GL_INVALID_OPERATION error generated. Cannot modify the default framebuffer object.