Initial fix of the crash with different map sizes but that's not the ultimate fix.

gui.cpp

@@ -5,6 +5,7 @@
 #include <string>                   // for string, operator<<
 #include <thread>                   // for sleep_for
 #include <array>
+#include <algorithm>
 
 #include <ftxui/dom/elements.hpp>  // for hflow, paragraph, separator, hbox, vbox, filler, operator|, border, Element
 #include <ftxui/dom/node.hpp>      // for Render
@@ -50,10 +51,13 @@ GUI::GUI(DinkyECS::World &world, Map& game_map) :
 void GUI::resize_map(int new_size) {
   if($renderer.resize_map(new_size)) {
     auto bounds = $renderer.$base_glyph.bounds;
-    $view_port = {
-      size_t(std::ceil((VIDEO_X - GAME_MAP_POS) / bounds.width)),
-      size_t(std::ceil(VIDEO_Y / bounds.height))
-    };
+    int view_x = std::ceil((VIDEO_X - GAME_MAP_POS) / bounds.width);
+    int view_y = std::ceil(VIDEO_Y / bounds.height);
+
+    // don't allow resizing beyond/below game map size
+    if(view_x > GAME_MAP_X || view_y > GAME_MAP_Y) return;
+
+    $view_port = {size_t(view_x), size_t(view_y)};
 
     // set canvas to best size
     $canvas = Canvas($view_port.x * 2, $view_port.y * 4);