message: Check the font path is the file
  If the font path is the directory then it's undefined behavior.
diff: @@ -58,13 +58,13 @@ ImGuiHelper::ImGuiHelper(Engine* engine, filament::View* view, const Path& fontP
  // If the given font path is invalid, ImGui will silently fall back to proggy, which is a
  // tiny "pixel art" texture that is compiled into the library.
  - if (!fontPath.isEmpty()) {
  + if (fontPath.isFile()) {
  io.Fonts->AddFontFromFileTTF(fontPath.c_str(), 16.0f);
  }
  createAtlasTexture(engine);
  // For proggy, switch to NEAREST for pixel-perfect text.
  - if (fontPath.isEmpty() && !imGuiContext) {
  + if (!fontPath.isFile() && !imGuiContext) {
  mSampler = TextureSampler(MinFilter::NEAREST, MagFilter::NEAREST);
  mMaterial->setDefaultParameter("albedo", mTexture, mSampler);
  }
  