Errors in func.yaml make a deployment fail at runtime, not at compile time #125

I had a func.yaml with the follwoing content:

name: mail
version: 0.0.3
runtime: java
cmd: com.espirit.fsi.example.ApplicationViaMail.java::handleRequest
build_image: fnproject/fn-java-fdk-build:jdk9-1.0.56
run_image: fnproject/fn-java-fdk:jdk9-1.0.56
format: http

an fn deploy, as well as fn test did not fail, however the docker image was not able to run because of the copy-paste-error in cmd, which contained the .java file extension which was wrong.

My expectation is that an fn test or fn deploy fails when it cannot run properly. One possible solution is to run the docker image locally before deploying it, although it may be possible to check the func.yaml direclty for correctness.