An NPE is thrown when JenkinsServer::getBuild doesn't have a build currently kicked off

java.lang.NullPointerException
    at com.offbytwo.jenkins.JenkinsServer.getBuild(JenkinsServer.java:810)
    at com.offbytwo.jenkins.JenkinsServer$getBuild$3.call(Unknown Source)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
    at ideaGroovyConsole.run(ideaGroovyConsole.groovy:64)
    at groovy.lang.GroovyShell.runScriptOrMainOrTestOrRunnable(GroovyShell.java:263)
    at groovy.lang.GroovyShell.run(GroovyShell.java:518)
    at groovy.lang.GroovyShell.run(GroovyShell.java:497)
    at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
 

Happens on the line:

String url = q.getExecutable().getUrl();