Index.html exception in productionMode Jmix 2.0

Support
#1

Jmix 2.0 - working with an application migrated from 1.5.

Switching to production mode generates this exception. I have an index.html file in the frontend directory. Application runs OK in development mode.

2023-09-30T16:31:23.082-04:00 ERROR 23392 --- [nio-8080-exec-8] c.v.flow.server.frontend.FrontendUtils   : Cannot get the 'index.html' from the classpath
2023-09-30T16:31:23.090-04:00 ERROR 23392 --- [nio-8080-exec-8] i.j.f.exception.UiExceptionHandlers      : There is no io.jmix.flowui.exception.UiExceptionHandler can handle the exception

java.io.UncheckedIOException: java.io.IOException: Unable to find index.html. It should be available on the classpath when running in production mode
	at com.vaadin.flow.server.communication.IndexHtmlRequestHandler$IndexHtmlHolder.<init>(IndexHtmlRequestHandler.java:417) ~[flow-server-24.0.9.jar:24.0.9]
#2

I may have figured out part of this. When deploying to AWS I had to build with productionMode=true and that worked, so I think I shall just stay with development mode on my workstation since that is what the app wants when starting it from IntelliJ.