1. Add a JDK in Global Tool Configuration (total 1)
2. Add a job (that uses it)
3. Edit Configuration Slicing - JDK per project
4. Remove the JDK from the Configured Value text area
5. Save

Results in Angry Butler. The root cause is a NullPointerException:

Caused by: java.lang.NullPointerException
at hudson.model.AbstractProject.setJDK(AbstractProject.java:944)
at configurationslicing.jdk.JdkSlicer$JdkSlicerSpec.setValues(JdkSlicer.java:67)
at configurationslicing.jdk.JdkSlicer$JdkSlicerSpec.setValues(JdkSlicer.java:26)
at configurationslicing.UnorderedStringSlicer.transform(UnorderedStringSlicer.java:100)
at configurationslicing.UnorderedStringSlicer.transform(UnorderedStringSlicer.java:6)
at configurationslicing.ConfigurationSlicing$SliceExecutor.transform(ConfigurationSlicing.java:136)
at configurationslicing.ConfigurationSlicing$SliceExecutor.doSliceconfigSubmit(ConfigurationSlicing.java:180)