neercs: clamp canvas size to ensure we never get to zero.

neercs/video/render.cpp

@@ -368,6 +368,7 @@ void Render::UpdateSize()
     screen_size = Video::GetSize();
     //border.y = border.x; // enabled to get same border everywhere
     canvas_char = (screen_size - border * 2) / (font_size * ratio_2d);
+    canvas_char = max(canvas_char, ivec2(1, 1));
     canvas_size = canvas_char * font_size * ratio_2d;
 
     border = (screen_size - canvas_size) / 2;
@@ -1126,4 +1127,4 @@ void Render::Draw3D()
 
 Render::~Render()
 {
-}
+}