Improved error-handling for extendable attributes & elements #1283

Job	Run time
PHP-Linter (8.4) / linter	9s
PHP-Linter (8.3) / linter	10s
PHP-Linter (8.5) / linter	12s
Linter / json-linter	27s
Linter / yaml-linter	5s
Linter / style-linter	0s
Linter / ecmascript-linter	0s
Unit tests, PHP 8.4, windows-latest	1m 2s
Unit tests, PHP 8.5, windows-latest	58s
Unit tests, PHP 8.3, windows-latest	1m 25s
Unit tests, PHP 8.5, ubuntu-latest	31s
Unit tests, PHP 8.4, ubuntu-latest	22s
Unit tests, PHP 8.3, ubuntu-latest	25s
Code coverage	7s
Security checks	19s
Quality control	39s
Cleanup artifacts	3s
	6m 54s

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