longcontrol: check if speeds is empty (#23410)

* check if speeds is empty

* move into existing check

Co-authored-by: Willem Melching <willem.melching@gmail.com>

selfdrive/controls/lib/longcontrol.py

@@ -68,8 +68,10 @@ class LongControl():
       a_target_upper = 2 * (v_target_upper - speeds[0])/CP.longitudinalActuatorDelayUpperBound - long_plan.accels[0]
       a_target = min(a_target_lower, a_target_upper)
 
+      v_target = speeds[0]
       v_target_future = speeds[-1]
     else:
+      v_target = 0.0
       v_target_future = 0.0
       a_target = 0.0
 
@@ -91,7 +93,7 @@ class LongControl():
 
     # tracking objects and driving
     elif self.long_control_state == LongCtrlState.pid:
-      self.v_pid = speeds[0]
+      self.v_pid = v_target
 
       # Toyota starts braking more when it thinks you want to stop
       # Freeze the integrator so we don't accelerate to compensate, and don't allow positive acceleration