Update end item before moving on track/via change

The move even dereferences m_enditem for logging and perhaps other
actions.  We need to ensure that the end item has not been invalidated
before taking this action

Fixes https://gitlab.com/kicad/code/kicad/issues/10732

(cherry picked from commit 901c330478)

pcbnew/router/router_tool.cpp

@@ -2065,6 +2065,8 @@ int ROUTER_TOOL::onTrackViaSizeChanged( const TOOL_EVENT& aEvent )
 
     // Changing the track width can affect the placement, so call the
     // move routine without changing the destination
+    // Update end item first to avoid moving to an invalid/missing item
+    updateEndItem( aEvent );
     m_router->Move( m_endSnapPoint, m_endItem );
 
     UpdateMessagePanel();