Nailgun prints out cryptic error messages about bloop HOT 9 CLOSED

$ cat bloop.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>Bloop</string>
    <key>Program</key>
    <string>/Users/ollie/dev/bloop/bloop-server</string>
    <key>KeepAlive</key>
    <true/>
</dict>
</plist>
$ launchctl load bloop.plist
$ alias bloop="ng bloop.Cli"
$ bloop help
<...> 

% bloop projects
Loading 4 projects from '/Users/evgeniy/<project_path>/.bloop-config'...
Projects loaded from '/Users/evgeniy/<project_path>/.bloop-config':
 * macros
 * macros-test
 * root
 * root-test
Dec 01, 2017 2:08:36 PM com.martiansoftware.nailgun.NGInputStream$1 run
WARNING: Nailgun client read future was interrupted
java.lang.InterruptedException
	at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:404)
	at java.util.concurrent.FutureTask.get(FutureTask.java:204)
	at com.martiansoftware.nailgun.NGInputStream$1.run(NGInputStream.java:91)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

Dec 01, 2017 2:08:36 PM com.martiansoftware.nailgun.NGSession run
INFO: NGSession shutting down