Fix VTOL Landing yaw param (#9279)

src/MissionManager/VTOLLandingComplexItem.cc

@@ -92,10 +92,11 @@ MissionItem* VTOLLandingComplexItem::_createLandItem(int seqNum, bool altRel, do
     return new MissionItem(seqNum,
                            MAV_CMD_NAV_VTOL_LAND,
                            altRel ? MAV_FRAME_GLOBAL_RELATIVE_ALT : MAV_FRAME_GLOBAL,
-                           0.0, 0.0, 0.0, 0.0,
+                           0.0, 0.0, 0.0,
+                           qQNaN(),         // Yaw - not specified
                            lat, lon, alt,
-                           true,                               // autoContinue
-                           false,                              // isCurrentItem
+                           true,            // autoContinue
+                           false,           // isCurrentItem
                            parent);
 
 }
@@ -109,7 +110,7 @@ bool VTOLLandingComplexItem::_isValidLandItem(const MissionItem& missionItem)
 {
     if (missionItem.command() != MAV_CMD_NAV_LAND ||
             !(missionItem.frame() == MAV_FRAME_GLOBAL_RELATIVE_ALT || missionItem.frame() == MAV_FRAME_GLOBAL) ||
-            missionItem.param1() != 0 || missionItem.param2() != 0 || missionItem.param3() != 0 || missionItem.param4() != 0) {
+            missionItem.param1() != 0 || missionItem.param2() != 0 || missionItem.param3() != 0 || !qIsNaN(missionItem.param4())) {
         return false;
     } else {
         return true;