Update self.last_pos_datetime handling

Updated all `self.last_pos_datetime` caculations to not exit the program if `ac_dict.time_position` is NoneType.

planeClass.py

@@ -88,6 +88,7 @@ class Plane:
             from mictronics_parse import get_aircraft_reg_by_icao, get_type_code_by_icao
             self.reg = get_aircraft_reg_by_icao(self.icao)
             self.type = get_type_code_by_icao(self.icao)
+            if ac_dict.time_position is not None:
                 self.last_pos_datetime = datetime.fromtimestamp(ac_dict.time_position)
         except ValueError as e:
             print("Got data but some data is invalid!")
@@ -544,6 +545,7 @@ class Plane:
         if self.feeding:
             #Squawks
             emergency_squawks ={"7500" : "Hijacking", "7600" :"Radio Failure", "7700" : "General Emergency"}
+            if self.last_pos_datetime is not None:
                 seen = datetime.now() - self.last_pos_datetime
             #Only run check if emergency data previously set
             if self.last_emergency is not None and not self.emergency_already_triggered:
@@ -567,6 +569,7 @@ class Plane:
             #Realizes first time seeing emergency, stores time and type
             elif self.squawk in emergency_squawks.keys() and not self.emergency_already_triggered and not self.on_ground:
                 print("Emergency", self.squawk, "detected storing code and time and waiting to trigger")
+                if self.last_pos_datetime is not None:
                     self.last_emergency = (self.last_pos_datetime, self.squawk)
             elif self.squawk not in emergency_squawks.keys() and self.emergency_already_triggered:
                 self.emergency_already_triggered = None