docs: fix exception handler examples not compiling

[FlorianCassayre]

References #3971 and #1465

The changes are analogous to the ones in the above-referenced PR. Additionally, I verified that no other examples were affected by a similar issue.

[lightbend-cla-validator]

Hi @FlorianCassayre,

Thank you for your contribution! We really value the time you've taken to put this together.

Before we proceed with reviewing this pull request, please sign the Lightbend Contributors License Agreement:

https://www.lightbend.com/contribute/cla

[FlorianCassayre]

(CLA signed)

[jrudolph]

After all this didn't compile correctly...

[FlorianCassayre]

Well, the example does compile but seems to trigger a warning in this workflow (which is interpreted as an error). I'll see what I can do.

[johanandren]

Close-open to retrigger validation

[johanandren]

Seems like a relevant compiler error:

[error] /home/runner/work/akka-http/akka-http/docs/src/test/scala/docs/http/scaladsl/server/ExceptionHandlerExamplesSpec.scala:165:64: Selecting value myExceptionHandler from object MyApp, which extends scala.DelayedInit, is likely to yield an uninitialized value [error] Get() ~> handleExceptions(MyExplicitExceptionHandler.MyApp.myExceptionHandler) {

[FlorianCassayre]

I see you're closing the PR, but do you have any fix for the underlying problem?

[johanandren]

Mostly closing because of inactivity, with no work pushed since almost a year I thought it was abandoned, if you still want to investigate/fix please re-open and push a fix that fixes the compilation error!