online-auction-scala | Lagom is a Swedish word meaning | Microservice library

Taking into account the comment by James Ward (see Overriding WebJar assets in Play 2.x), I "solved" the issue by:

a) removing the dependency in build.sbt ("org.webjars" % "foundation" % "6.4.3-1")

b) creating and using a 'custom download' of foundation (https://foundation.zurb.com/sites/download.html/#customizeFoundation)

Persistent entity command handlers and after persist callbacks are wrapped in try/catch blocks, if an exception is caught, it will pass that exception to ctx.commandFailed(...) for you.

There is a subtle difference between the two to be aware of. If you throw an exception, processing of the command will of course stop immediately. If however you pass an exception to ctx.commandFailed(...), that will send the exception back to the invoker of the command, however it won't stop processing. You could in theory go on to return some directives to persist events - which would be an odd thing to do. In practice what you need to do is return ctx.done after invoking ctx.commandFailed(...).

In general it's probably simpler and safer to simply throw the exception.