When your flow is running, nodes may throw exceptions. To handle these exceptions you can use a Catch node.
Below example shows a simple exception caused by not providing a file path for the Open Excel node.
Error details can be seen below in the Debug panel.
To handle these errors you can use a special node named "Catch"
Catch nodes catch exceptions selectively. You can catch the exceptions from the nodes you want by only selecting the nodes from the properties panel of the Catch node.
The message object injected from the Catch node will include the error field that can be used to decide what to do next.
If you want to not use a catch node and want the node to continue flow without throwing an exception than you can select "Continue on Error" option in the Common section of the node you want to ignore errors.
If this option is selected, node will not throw an exception and continue the flow as below: