Custom Web Item - Static Type checker won't return result

When pasting in the path to a script in the "Custom web item" script fragment form, the static type checker starts running, as expected. It stops running and the space where the result should be is blank. The following exception is thrown:

2017-12-11 15:39:29 [http-nio-8080-exec-4] ERROR c.a.p.r.c.e.j.ThrowableExceptionMapper - Uncaught exception thrown by REST service: Cannot get property 'name' on null object

java.lang.NullPointerException: Cannot get property 'name' on null object

at com.onresolve.scriptrunner.canned.common.StaticCompilationChecker.doScript(StaticCompilationChecker.groovy:106)

Tested on Bitbucket v5.0.0