So your query with the large where-clause produces a Query Result tab just fine, but then following up with a right-click and Export... from it's context menu fails with a null pointer (basically Java is seeing a null for output xlsx file path) exception?
As far as I know (from reading other answers on export), an export will run the SQL query again unless the Query Result tab contains all rows. For example, if I do this ...
... I get the first 200 rows, but if I select a cell in the result and press Ctrl-End all the rows will load ...
so that all 73,127 rows of the result set are in memory. An export at this point will not rerun the query. So my question is, if you do the "select a cell in the result and press Ctrl-End" does that succeed or does something fail along the way? You can also try launching SQL Developer from the command line and see if any additional error messages appear in the Cmd window.
And if that does not work, try spooling to a csv file as Jeff Smith suggests in