Added exception handling for when an error occurs in the waternet calculation. Related to Issue [WTI-1345]git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@12104 5a3db67b-de53-47b5-99c8-a1c30a6650e2Former-commit-id: 3b5ea5941b0d4a38e68f199924dbc5ba239b090aFormer-commit-id: 2f2522a0c6d89d076271eed46e061669c7520dff