Fix NullPointerException in MethodsFunctionsChecker

[rcosta358]

This PR fixes an issue where when a class had multiple methods and one method would throw an error related to a parametric refinement (e.g., InvalidRefinementError), the exception would abort the visitation of sibling methods during the first pass. Then, in second pass, when trying to get the function that should have been added to the context in the first pass, it is not there, and would throw a NullPointerException. This was because there were missing try-catch blocks in the getMethodRefinements and getConstructorRefinements (in this case, the first one).

Example Reproduction

public class SimpleTest {

    void testParam(@Refinement("y + 1") int y) {}

    int test() {
        return -1;
    }
}
// Cannot invoke "liquidjava.processor.context.RefinedFunction.getArguments()" because "fi" is null

[rcosta358]

Just in case.

[rcosta358]

We cannot assume this anymore because a method that throws InvalidRefinementError on a parametric refinement will not be added to the context.