Why not checking for the ``JavaModelException``?

The JavaDoc for ``IJavaProject#getRawClasspath`` says that it throws a ``JavaModelException`` *if this element does not exist or if an
exception occurs while accessing its corresponding resource*. Hence, I feel that checking if the project is open does not cover the whole space.
My suggestion would be to rewrite it as

```scala
try javaProject.getResolvedClasspath(true).toList // List.fromArray is deprecated in Scala 2.10
catch {
  case e: JavaModelException => logger.debug(e); Nil
}
```

WDYT?

If you agree with the above, I think the same should be done for ``clearSettingsErrors``, ``clearAllBuildProblemMarkers``, ... (check the JavaDoc for ``IResource#deleteMarkers``.