ExplicitResultTypes silently does nothing with invalid classpath

[jackkoenig]

I found that ExplicitResultTypes will silently do nothing when there is a problem with the classpath. In my particular case my classpath had:
scala-compiler-2.13.14.jar, scala-reflect-2.13.16.jar, and scalafix-reflect_2.13.14-0.12.1.jar, basically the incorrect scala-reflect for the version of scalafix I am using.

Fixing scala-reflect to be 2.13.14 fixed the issue.

What helped was enabling fatalWarnings:

ExplicitResultTypes.fatalWarnings = true

With this on, ScalaFix did crash and report an error:

info: Processing (0/1) /.../MyFile.scala
scalafix.internal.v1.FileException: unexpected error processing file /.../MyFile.scala
Caused by: scalafix.internal.rule.CompilerException: compiler crashed
    at scalafix.internal.rule.CompilerTypePrinter.toPatch(CompilerTypePrinter.scala:36)
    at scalafix.internal.rule.ExplicitResultTypes.$anonfun$defnType$2(ExplicitResultTypes.scala:204)
    ...
Caused by: java.lang.NoClassDefFoundError: scala/reflect/internal/tpe/TypeMaps$ContainsAnyCollector
    at scala.tools.nsc.typechecker.Typers$Typer.<init>(Typers.scala:211)
    at scala.tools.nsc.interactive.InteractiveAnalyzer$$anon$1.<init>(Global.scala:50)
    at scala.tools.nsc.interactive.InteractiveAnalyzer.newTyper(Global.scala:50)
    ...
Caused by: java.lang.ClassNotFoundException: scala.reflect.internal.tpe.TypeMaps$ContainsAnyCollector
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
    ... 71 more

The key being here that scala/reflect/internal/tpe/TypeMaps$ContainsAnyCollector exists in scala-reflect 2.13.14 but not scala-reflect 2.13.16.

Thanks to @bjaglin for advice on Discord that helped me figure this out!