dig anchor when separated from a wall

mods/pmb_nodes/pmb_rope/init.lua

@@ -103,7 +103,11 @@ minetest.register_node('pmb_rope:rope_anchor', {
   use_texture_alpha = "clip",
   sounds = pmb_sounds.default_stone(),
   climbable = true,
-  -- _on_node_update = pmb_rope.rope_update,
+  _on_node_update = function(pos, cause, user, count, payload)
+    if pmb_util.has_adjacent(pos, "solid") == 0 then
+      minetest.dig_node(pos)
+    end
+  end,
   on_place = function(itemstack, placer, pointed_thing)
     minetest.rotate_and_place(itemstack, placer, pointed_thing)
   end,