An app for a particular getdown channel can't launch builds from other channels due to failed background image downloads

Not sure if this is a systemic problem as yet - could be because we are working with multiple different versions of getdown.

Jalview's build server has a getdown plan channel and a DEVELOP installer getdown channel (JAL-4409) - and each channel has a distinct set of background images (JAL-3594).

What this means is you need to use the correct CHANNEL= setting when building a getdown channel for the launcher that will run it. Otherwise, the launch fails with messages such as the one below in launcher.log:
2024/07/04 15:10:04:546 WARNING Download failed [rsrc=resource/jalview_develop_getdown_progress_bar.png, java.io.IOException: Unable to download resource https://builds.jalview.org/browse/JB-GDL2/latest/artifact/shared/getdown/resource/jalview_develop_getdown_progress_bar.png: 404=<toString() failure: java.lang.ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3>]
java.io.IOException: Unable to download resource https://builds.jalview.org/browse/JB-GDL2/latest/artifact/shared/getdown/resource/jalview_develop_getdown_progress_bar.png: 404
        at com.threerings.getdown.net.HTTPDownloader.download(HTTPDownloader.java:71)