Reproducing:

• Add a WOFF font, such as Xolonium, to Samples/assets
• Add { "Xolonium-Regular.woff", false }, to the font faces list in Shell.cpp
• Launch and close any sample

Looks like FreeType::ReleaseFace expects FT_Face->stream->base to hold a pointer to the data pointer that was passed in but in the case of WOFF fonts it doesn't.