feed cell viability tuple

src/Mono.cs

@@ -190,7 +190,7 @@ static class Mono
         }
     }
 
-    static void Feed()
+    static (bool, XYZi) Feed()
     {
         // [!] handle out of the box exception on tail
         // by making the spatial arrays encapsulate the layer outside of the box
@@ -199,6 +199,7 @@ static class Mono
 
         // step from head using directions towards the tail
         // and stop at either 1 cell away from the tail or 5 spaces away from the head
+        bool viable = false;
         XYZi cell = snake[0];
         for (int step = 0; step < 5; step++)
         {
@@ -214,6 +215,7 @@ static class Mono
                 {
                     min_dist = tail_dist;
                     min_cell = dir_cell;
+                    viable = true;
                 }
             }
             cell = min_cell;
@@ -223,7 +225,9 @@ static class Mono
             // }
         }
 
-        food = cell;
+        // [!] if can't find a viable cell try again next step
+        // (as it is possible to fence in the tail esp if you are eating)
+        return (viable, cell);
     }
 
     // space fill algorithm