(JPackager on n Windows platform)
It is not really clear what the argument to --app-image is supposed to be.
The help text is:
  --app-image
          Location of the predefined application image that is used to build
          an installable package.

When trying to use the output from a packager create-image command, or various other directories or executable files, it just gets an exception saying there was a problem running light.exe

java.io.IOException: Exec failed with code 103 command [[C:\cygwin\home\aherrick\devtools\wix35-binaries\light.exe, -dWixUILicenseRtf=license.txt, -nologo, -spdb, -sice:60, C:\cygwin\home\aherrick\packager\temp\all\tmp\license.wixobj, -ext, WixUtilExtension, -ext, WixUIExtension.dll, -out, C:\cygwin\home\aherrick\packager\output\license\license-1.0.msi] in C:\cygwin\home\aherrick\packager\output\simple
        at jdk.packager/jdk.packager.internal.IOUtils.exec(IOUtils.java:219)
        at jdk.packager/jdk.packager.internal.IOUtils.exec(IOUtils.java:187)
        at jdk.packager/jdk.packager.internal.IOUtils.exec(IOUtils.java:182)
        at jdk.packager/jdk.packager.internal.windows.WinMsiBundler.buildMSI(WinMsiBundler.java:1190)
        at jdk.packager/jdk.packager.internal.windows.WinMsiBundler.bundle(WinMsiBundler.java:585)
        at jdk.packager/jdk.packager.internal.windows.WinMsiBundler.execute(WinMsiBundler.java:271)
        at jdk.packager/jdk.packager.internal.Arguments.generateBundle(Arguments.java:634)
        at jdk.packager/jdk.packager.internal.Arguments.processArguments(Arguments.java:578)
        at jdk.packager/jdk.packager.Main.run(Main.java:159)
        at jdk.packager/jdk.packager.Main.main(Main.java:131)

This output does not help the developer to know what arg is at fault (in this case the app-image arg) or what can be done about it.