Not all views can have a sheet number (legends, schedules, and I believe templates can be caught by the method you are using), so issues with that don’t surprise me too much. What is the error? Can you expand the watch node and find where the odd values are, and confirm that the elements causing the error do so in a consistent and understandable way?
You appear to be waiting for a view type before passing the list of element IDs through to the next tool eraser node, is this correct? Feels somewhat backwards.
If you want to use the the output of the first tool.eraser node to work with the elements which failed to delete, you may need to do some conversion. I believe that the output of this node is a list of Element Ids as a string, not Revit elements. You can confirm this with an Object.Type node. If it is than you will have to convert the IDs to elements (IDs to element in I think archilab will do that for you).