Fix harvesting errors not always being reported

[tobias-hotz]

This Pull Request fixes an issue with the way how harvesters report their errors.
Currently, there are two lists that may contain error, one in AbstractHarvester and one in many harvester classes. The intent is to merge these two lists in AbstractHarvester via the getErrors() method.
This, however, does not work, as getErrors always returns the List that is present in AbstractHarvester. There seems to be an inheritance issue here: The subclasses of AbstractHarvester do not implement getErrors themself, but the classes that are called by the subclasses.
Let's take the CSW Harvester as an example: The subclass of AbstractHarvester CswHarvester does not override getErrors, but it contructs an instace of Harvester, which is an instace of IHarvester. IHarvester and AbstractHarvester are two distinct classes, and as the CSWHarvester does not forward the errors of the newly created Harvester, these errors are just lost.

This means that many errors just get swallowed, and in some cases a harvesting run seems successful, but upon closer inspection (log or harvesting result), there was actually an error!

The fix is simple: just give the actual IHarvester implementations a reference to the same error list that AbstractHarvester uses.

Checklist

• I have read the contribution guidelines
• Pull request provided for main branch, backports managed with label
• Good housekeeping of code, cleaning up comments, tests, and documentation
• Clean commit history broken into understandable chucks, avoiding big commits with hundreds of files, cautious of reformatting and whitespace changes
• Clean commit messages, longer verbose messages are encouraged
• API Changes are identified in commit messages
• Testing provided for features or enhancements using automatic tests
• User documentation provided for new features or enhancements in manual
• Build documentation provided for development instructions in README.md files
• Library management using pom.xml dependency management. Update build documentation with intended library use and library tutorials or documentation

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Funded by LGL BW

[josegar74]

Thanks @tobias-hotz the code changes look good and now the errors are stored inthe harvester history table.

Without the pull request in the harvest history table, no errors are stored, while checking the log file there are errors:

    <logfile>harvester_csw_CSWErrorTest_20250214121701.log</logfile>
    <errors />

With the pull request:

   <logfile>harvester_csw_CSWErrorTest_20250214121952.log</logfile>
    <errors>
        <error>
            <description>java.lang.RuntimeException: java.lang.NullPointerException</description>
            <hint>Check with your administrator the error.</hint>
            ...