Type of pull request

• Bug fix (involves code and configuration changes)
• New feature (involves code and configuration changes)
• Documentation update
• Something else

About

Adding 2 dedicated exceptions, following the path of #433

2 remarks:

• Please create a file CONTRIBUTING.md, according to https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors and include all information from the checklist (here below)
• I don't know how to run the unit tests, nor cs-fixer.

Checklist for code / configuration changes

In case you changed the code/configuration, please read each of the following checkboxes as they contain valuable information:

• Please add at least one test case (unit test, system test, ...) to demonstrate that the change is working. If existing code was changed, your tests cover these code parts as well.
  By the way, you don't have to provide a full fledged PDF file to demonstrate a fix. Instead a unit test may be sufficient sometimes,
  please have a look at FontTest for example code.
  Code changes without any tests are likely to be rejected. If you dont know how to write tests, no problem, tell us upfront and we may add them ourselves or discuss other ways.
• Please run PHP-CS-Fixer before committing, to confirm with our coding styles. See https://github.com/smalot/pdfparser/blob/master/.php-cs-fixer.php for more information about our coding styles.
• In case you fix an existing issue, please do one of the following:
  • Write in this text something like fixes #1234 to outline that you are providing a fix for the issue #1234.
  • After the pull request was created, you will find on the right side a section called Development. There issues can be selected which will be closed after the your pull request got merged.
• In case you changed internal behavior or functionality, please check our documentation to make sure these changes are documented properly: https://github.com/smalot/pdfparser/tree/master/doc
• In case you want to discuss new ideas/changes and you are not sure, just create a pull request and mark it as a draft
  (see here for more information).
  This will tell us, that it is not ready for merge, but you want to discuss certain issues.