Bulk output flag throws error

While trying to deduplicate the output (cf. #7), I tried running MappingWeaver with the --bulk flag, only to find that enabling this option immediately results in an error:

Exception in thread "main" java.lang.RuntimeException: java.lang.ClassCastException: class java.lang.Boolean cannot be cast to class java.lang.String (java.lang.Boolean and java.lang.String are in module java.base of loader 'bootstrap')
        at be.ugent.idlab.knows.mappingweaver.cli.Main.parseAndRun(Main.java:172)
        at be.ugent.idlab.knows.mappingweaver.cli.Main.main(Main.java:58)
Caused by: java.lang.ClassCastException: class java.lang.Boolean cannot be cast to class java.lang.String (java.lang.Boolean and java.lang.String are in module java.base of loader 'bootstrap')
        at be.ugent.idlab.knows.mappingweaver.cli.Main.parseAndRun(Main.java:106)
        ... 1 more

The culprit seems to be an implicit type cast when parsing the option in mappingweaver/cli/Main.java#L106.

Start with src/main/java/be/ugent/idlab/knows/mappingweaver/cli/Main.java, especially the option parsing at line 106, and reproduce the failure using the --bulk flag. Trace the parsed value and verify that enabling --bulk no longer produces the reported ClassCastException and allows the command to run.