Try this:

• Create an empty file called Example.fan.
• Run it as a Fantom script: C:\> fan Example.fan
• Receive stack trace:

  ERROR: cannot compile script
  sys::NullErr: java.lang.NullPointerException
    fan.sys.Pod.load (Pod.java:403)
    fan.sys.Pod.<init> (Pod.java:217)
    fan.sys.Pod.load (Pod.java:130)
    compiler::LoadPod.load (LoadPod.fan:53)
    compiler::GenerateOutput.run (GenerateOutput.fan:43)
    compiler::Compiler.backend (Compiler.fan:115)
    compiler::Compiler.compile (Compiler.fan:67)
    compiler::Main.compileScript (Main.fan:52)
    java.lang.reflect.Method.invoke (Method.java:597)
    fan.sys.Method.invoke (Method.java:559)
    fan.sys.Method$MethodFunc.call (Method.java:297)
    fan.sys.Method.call (Method.java:143)
    fanx.util.EnvScripts.compile (EnvScripts.java:87)
    fanx.util.EnvScripts.compile (EnvScripts.java:45)
    fan.sys.Env.compileScript (Env.java:139)
    fanx.tools.Fan.compileScript (Fan.java:112)
    fanx.tools.Fan.executeFile (Fan.java:79)
    fanx.tools.Fan.execute (Fan.java:37)
    fanx.tools.Fan.run (Fan.java:298)
    fanx.tools.Fan.main (Fan.java:336)

While technically, yes the error msg is correct, I think the stacktrace and NullPointerException is a bit misleading and could be handled better.

Thanks for reporting that, I pushed a fix