LabelPlugValueWidget : Ignore errors when trying to determine the value changed An error when calling Gaffer.NodeAlgo.isSetToUserDefault() or plug.isSetToDefault() was causing the ui to fail to build. It seems better to catch the errors at those two points since they are almost certainly related to an error during the plug.getValue() call, which itself is likely an error during compute() (for output plugs) or in an expression node (for input plugs), and in both cases, the error will be handled by the ValuePlugWidget and the Node. An alternative considered was to add the exception handling to the isSetUserDefault() and isSetToDefault() themselves, but that seems like a worse option since when calling such methods from outside a ui building context, it's likely we do want the exception to be raised.
LabelPlugValueWidget : Ignore errors when trying to determine the value changed
An error when calling Gaffer.NodeAlgo.isSetToUserDefault() or
plug.isSetToDefault() was causing the ui to fail to build.
It seems better to catch the errors at those two points since they are almost
certainly related to an error during the plug.getValue() call, which itself is
likely an error during compute() (for output plugs) or in an expression node
(for input plugs), and in both cases, the error will be handled by the
ValuePlugWidget and the Node.
An alternative considered was to add the exception handling to the
isSetUserDefault() and isSetToDefault() themselves, but that seems like a worse
option since when calling such methods from outside a ui building context, it's
likely we do want the exception to be raised.

hradec/gaffer,boberfly/gaffer,appleseedhq/gaffer,boberfly/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,ivanimanishi/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,hradec/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,boberfly/gaffer,chippey/gaffer,andrewkaufman/gaffer,hradec/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,chippey/gaffer,chippey/gaffer,lucienfostier/gaffer,lucienfostier/gaffer,chippey/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,ivanimanishi/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,hradec/gaffer,appleseedhq/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,ImageEngine/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,boberfly/gaffer,GafferHQ/gaffer,hradec/gaffer