HPCC-10831 Activity Page Refresh Issues

Tree is throwing an exception if a child node is refreshed.

Fixes HPCC-10831

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #5735 from GordonSmith/HPCC-10831

HPCC-10831 Activity Page Refresh Issues

Reviewed-By: Kevin Wang <kevin.wang@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>