Improved error-handling for extendable attributes & elements #1284

Job	Run time
PHP-Linter (8.5) / linter	14s
Linter / json-linter	26s
PHP-Linter (8.4) / linter	14s
PHP-Linter (8.3) / linter	13s
Linter / yaml-linter	5s
Linter / style-linter	0s
Linter / ecmascript-linter	0s
Unit tests, PHP 8.4, windows-latest	57s
Unit tests, PHP 8.5, ubuntu-latest	32s
Unit tests, PHP 8.3, windows-latest	52s
Unit tests, PHP 8.4, ubuntu-latest	19s
Unit tests, PHP 8.5, windows-latest	59s
Unit tests, PHP 8.3, ubuntu-latest	27s
Security checks	17s
Code coverage	8s
Quality control	41s
Cleanup artifacts	3s
	6m 27s

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