Fix segfault by moving "register" to the update call, rather than the draw one

main.rb

@@ -217,10 +217,12 @@ class Hex
     @hexid = SecureRandom.uuid
     @dead = false
   end
-  
+  def update
-  def draw
     amidead?
     $hex_bgs.register(@hexid, @text_props.bg_color)
+  end
+  def draw
+    amidead?
     $hex_bgs[@text_props.bg_color].draw(
       @x, @y, 0, 1, 1, Gosu::Color::WHITE
     ) # layer 0: hex-bg
@@ -344,6 +346,13 @@ class HexagonTerminalWindow < Gosu::Window
       end
       print "\x1b[G\x1b[2K#{out}\x1b[#{new_text[2]+1}G"
     end
+    
+    # End of update should call hex updates
+    @hexes.each do |rex|
+      rex.each do |hex|
+        hex.update
+      end
+    end
   end
 
   def draw