Gracefully produce 404 error page for URLs with unknown vocabulary ID

[osma]

This PR fixes a problem with URLs containing vocabulary IDs that are unknown to Skosmos. (This includes things like script kiddie attacks looking for WordPress installations and the like.)

Example: https://finto.fi/notfound/ -> produces a blank page and a message in the server error log:

[Wed Oct 06 10:15:19.928508 2021] [php7:error] [pid 16194] [client 127.0.0.1:58340] PHP Fatal error:  Uncaught ValueError: Vocabulary id 'notfound' not found in configuration. in /var/www/finto.fi/model/Model.php:420\nStack trace:\n#0 /var/www/finto.fi/model/Request.php(246): Model->getVocabulary('notfound')\n#1 /var/www/finto.fi/index.php(51): Request->setVocab('notfound')\n#2 {main}\n  thrown in /var/www/finto.fi/model/Model.php on line 420

The reason is that the code in index.php attempts catch Exception, but nowadays (since PR #1127) ValueError is produced instead and it is a subclass of Error, not Exception.

This one-line fix changes the catch block to also include ValueError. The end result is that a 404 page is produced instead of a blank page, and nothing gets written into the error log.

(credit to @kouralex for pointing this out)

[codecov]

Codecov Report

Merging #1215 (9ac8831) into master (6688f21) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1215   +/-   ##
=========================================
  Coverage     68.36%   68.36%           
  Complexity     1619     1619           
=========================================
  Files            32       32           
  Lines          3973     3973           
=========================================
  Hits           2716     2716           
  Misses         1257     1257           

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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0.0% Duplication