Render heightmap to layer

src/image.cpp

@@ -25,6 +25,8 @@ bool Image::load_file(std::string filename)
 {
     stbi_set_flip_vertically_on_load(false);
     uint8_t* buffer = stbi_load(filename.c_str(), &width, &height, nullptr, 4);
+    if (!buffer)
+        return false;
     comp = 4;
     m_data = std::unique_ptr<uint8_t[]>(buffer);
     return true;