DIALOG_CONFIGURE_PATHS: Fix crash when deleting the last item in list.

When the list (in 3D search path list) contains only one item, when trying
to remove this last item, the crash happened.

common/dialogs/dialog_configure_paths.cpp

@@ -413,8 +413,12 @@ void DIALOG_CONFIGURE_PATHS::OnDeleteSearchPath( wxCommandEvent& event )
     m_SearchPaths->CommitPendingChanges( true /* silent mode; we don't care if it's valid */ );
     m_SearchPaths->DeleteRows( curRow, 1 );
 
-    m_SearchPaths->MakeCellVisible( std::max( 0, curRow-1 ), m_SearchPaths->GetGridCursorCol() );
-    m_SearchPaths->SetGridCursor( std::max( 0, curRow-1 ), m_SearchPaths->GetGridCursorCol() );
+    // if there are still rows in grid, make previous row visible
+    if( m_SearchPaths->GetNumberRows() )
+    {
+        m_SearchPaths->MakeCellVisible( std::max( 0, curRow-1 ), m_SearchPaths->GetGridCursorCol() );
+        m_SearchPaths->SetGridCursor( std::max( 0, curRow-1 ), m_SearchPaths->GetGridCursorCol() );
+    }
 }