FIX: init_font crash

Change-Id: I2d2fd9f297e2980e789b124d3e026d0db1fa1602

src/slic3r/GUI/ImGuiWrapper.cpp

@@ -1979,6 +1979,7 @@ void ImGuiWrapper::init_font(bool compress)
     unsigned char* pixels;
     int width, height;
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bits (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
+    BOOST_LOG_TRIVIAL(trace) << "Build texture done. width: " << width << ", height: " << height;
 
     // Fill rectangles from the SVG-icons
     for (auto icon : font_icons) {