Ref https://github.com/sbt/sbt/issues/4121
sbt already has the facility to trim stack traces. This sets the trace level of the background run, which fixes the upper half of the `run` stacktrace.
```
[error] (run-main-0) java.lang.Exception
[error] java.lang.Exception
[error] at Hello$.delayedEndpoint$Hello$1(Hello.scala:5)
[error] at Hello$delayedInit$body.apply(Hello.scala:1)
[error] at scala.Function0.apply$mcV$sp(Function0.scala:34)
[error] at scala.Function0.apply$mcV$sp$(Function0.scala:34)
[error] at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
[error] at scala.App.$anonfun$main$1$adapted(App.scala:76)
[error] at scala.collection.immutable.List.foreach(List.scala:389)
[error] at scala.App.main(App.scala:76)
[error] at scala.App.main$(App.scala:74)
[error] at Hello$.main(Hello.scala:1)
[error] at Hello.main(Hello.scala)
[error] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[error] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error] at java.lang.reflect.Method.invoke(Method.java:498)
[error] java.lang.RuntimeException: Nonzero exit code: 1
[error] at sbt.Run$.executeTrapExit(Run.scala:127)
[error] at sbt.Run.run(Run.scala:77)
[error] at sbt.Defaults$.$anonfun$bgRunTask$5(Defaults.scala:1254)
[error] at sbt.Defaults$.$anonfun$bgRunTask$5$adapted(Defaults.scala:1249)
[error] at sbt.internal.BackgroundThreadPool.$anonfun$run$1(DefaultBackgroundJobService.scala:377)
[error] at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
[error] at scala.util.Try$.apply(Try.scala:209)
[error] at sbt.internal.BackgroundThreadPool$BackgroundRunnable.run(DefaultBackgroundJobService.scala:299)
[error] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[error] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[error] at java.lang.Thread.run(Thread.java:748)
[error] (Compile / run) Nonzero exit code: 1
```
The bottom half requires a similar fix to the foreground log.
scalafmt is configured to use lf, as your editor should be, so there is no point having git tinker with line endings
otherwise on checkout on windows source files get converted to crlf (by git) and on compile they get converted back to lf (by scalafmt)
Fixes https://github.com/sbt/sbt/issues/3508
This forks an instance of sbt in the background when it's not running already.
```
$ time sbt -client compile
Getting org.scala-sbt sbt 1.2.0-SNAPSHOT (this may take some time)...
:: retrieving :: org.scala-sbt#boot-app
confs: [default]
79 artifacts copied, 0 already retrieved (28214kB/130ms)
[info] entering *experimental* thin client - BEEP WHIRR
[info] server was not detected. starting an instance
[info] waiting for the server...
[info] waiting for the server...
[info] server found
> compile
[success] completed
sbt -client compile 9.25s user 2.39s system 33% cpu 34.893 total
$ time sbt -client compile
[info] entering *experimental* thin client - BEEP WHIRR
> compile
[success] completed
sbt -client compile 3.55s user 1.68s system 107% cpu 4.889 total
```
Teo Klestrup Röijezon
eugene yokota
Sean Sullivan
Jason Pickens
OlegYch
Michael Pollmeier
Loïc Girault
Yi Cheng