Weird light switching off

Setup, Configuration and Use Scripts & Rules
3

Ok a few issues in the rule:

  • Use == instead of ===. Use == for OH states like NULL, ON…, Use === for java null
  • Add .toString in your colour command: BedroomLight_Color.sendCommand(def_hue.state.toString + "," + def_sat.state.toString + "," + new_bri)
  • VERY dangerous to use a loooonnnng Thread::sleep like this: Why have my Rules stopped running? Why Thread::sleep is a bad idea
    Use a timer instead
rule "bedroom_light_off"
when
    Item BedroomPresence changed to OFF
then
    logInfo("bedroom.rules", "Presence no longer detected")
    if (Film_Scene.state == ON) {
        logInfo("bedroom.rules", "But film is running, exiting")
        return;
    } else {
        logInfo("bedroom.rules", "Moving on, film is not running")
        if (Sun.state == OFF) {
            logInfo("bedroom.rules", "And the Sun is down, dimming")
            var new_bri = (Math.round(Integer::parseInt(def_bri.state.toString) / 2)).toString
            BedroomLight_Color.sendCommand(def_hue.state.toString + "," + def_sat.state.toString + "," + new_bri)
            //Thread::sleep(90000)
            createTimer(now.plusSeconds(90), [ |
                if (BedroomPresence.state == OFF) {
                    logInfo("bedroom.rules", "Presence is still off, switching light off")
                    BedroomLight_Color.sendCommand(OFF)
                }
            ])
        }
        else if (BedroomPresence.state == OFF) {
            logInfo("bedroom.rules", "Sun is not down, simply switching off")
            BedroomLight_Color.sendCommand(OFF)
        }
    }
end

If the item Film_Scene has no binding, it make no sense to send a command to it.
And you can combine these two rules into one:

rule "bedroom presence"
when
   Item BedroomMovement_MotionStatus changed or
   Item BedroomPCMovement_MotionStatus changed
then
    if (BedroomPCMovement_MotionStatus.state == ON || BedroomMovement_MotionStatus.state == ON) {
        BedroomPresence.postUpdate(ON)
    } else if (BedroomPCMovement_MotionStatus.state == OFF && BedroomMovement_MotionStatus.state == OFF) {
        BedroomPresence.postUpdate(OFF)
    }
end