RC_Channel: return MAV_RESULT_FAILED from do_aux_function if invalid function

libraries/RC_Channel/RC_Channel.cpp

@@ -893,7 +893,7 @@ void RC_Channel::do_aux_function_mission_reset(const AuxSwitchPos ch_flag)
     mission->reset();
 }
 
-void RC_Channel::do_aux_function(const aux_func_t ch_option, const AuxSwitchPos ch_flag)
+bool RC_Channel::do_aux_function(const aux_func_t ch_option, const AuxSwitchPos ch_flag)
 {
     switch(ch_option) {
     case AUX_FUNC::CAMERA_TRIGGER:
@@ -1150,8 +1150,10 @@ void RC_Channel::do_aux_function(const aux_func_t ch_option, const AuxSwitchPos
 
     default:
         gcs().send_text(MAV_SEVERITY_INFO, "Invalid channel option (%u)", (unsigned int)ch_option);
-        break;
+        return false;
     }
+
+    return true;
 }
 
 void RC_Channel::init_aux()

libraries/RC_Channel/RC_Channel.h

@@ -241,7 +241,7 @@ public:
     bool read_6pos_switch(int8_t& position) WARN_IF_UNUSED;
     AuxSwitchPos get_aux_switch_pos() const;
 
-    virtual void do_aux_function(aux_func_t ch_option, AuxSwitchPos);
+    virtual bool do_aux_function(aux_func_t ch_option, AuxSwitchPos);
 
 #if !HAL_MINIMIZE_FEATURES
     const char *string_for_aux_function(AUX_FUNC function) const;
@@ -482,8 +482,8 @@ public:
 
     uint32_t last_input_ms() const { return last_update_ms; };
 
-    void do_aux_function(RC_Channel::AUX_FUNC ch_option, RC_Channel::AuxSwitchPos pos) {
+    bool do_aux_function(RC_Channel::AUX_FUNC ch_option, RC_Channel::AuxSwitchPos pos) {
-        rc_channel(0)->do_aux_function(ch_option, pos);
+        return rc_channel(0)->do_aux_function(ch_option, pos);
     }
 
 protected: