CopyArtifact 1.4.1 will crash with a NullPointerException on CopyArtifact.java line 441 if the job config XML is missing <target>. This is a problem because JJB version =18.104.22.168b3.201803131321 doesn't write that tag if "target: null".
This should be easily fixable if we can modify and test the Copy Artifact plugin on Jenkins.
The crashing line of code is:
if (target.length() > 0) targetDir = new FilePath(targetDir, env.expand(target));