messages-perl fixes after Gherkin integration

[ehuelsmann]

Summary

Based on integration work into Gherkin/Perl, a few issues were identified that this PR fixes.

Motivation and Context

How Has This Been Tested?

Using my (locally available) integration in Gherkin/Perl.

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist:

• The change has been ported to Java.
• The change has been ported to Ruby.
• The change has been ported to JavaScript.
• The change has been ported to Go.
• The change has been ported to .NET.
• I've added tests for my code.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have updated the CHANGELOG accordingly.

[ehuelsmann]

Based on @aurelien-reeves's approval, merging.