Sometimes I get Stack trace of root exception is empty; this is likely due to a JVM optimization that can be disabled with -XX:-OmitStackTraceInFastThrow. when I execute code in the repl in cider. Any idea what I add to my build.boot in order to allow these stacktraces?

you could start your jvm with -XX:-OmitStackTraceInFastThrow

@samedhi You can use an environment variable to tell Boot to pass that to the JVM:

BOOT_JVM_OPTIONS=-XX:-OmitStackTraceInFastThrow