Adds time_in_current_state to Entity; Fixes removed users from Resources.

Author: sabvdf

datasim/entity.py

@@ -155,6 +155,10 @@ def _tick(self):
                 self._state.tick()
         self.ticks_in_current_state += 1
 
+    @property
+    def time_in_current_state(self) -> float:
+        return self.ticks_in_current_state / self.world.tpu
+
     def _change_state(self, new_state: "State | None"):
         if self._state == new_state:
             return

datasim/resource.py

@@ -278,6 +278,8 @@ def remove_user(self, user: Entity) -> bool:
 
     def usage_tick(self, user: Entity) -> bool:
         """Override this function for more complex usage time than a flat number of time units."""
+        if user not in self.users:
+            return False
         index = self.user_index[user]
         left = self.simple_time_left[index]
         left -= self.world.tick_time