TYPO3 Core

\TYPO3\CMS\Core\Package\PackageManager::getComposerManifest() calls \TYPO3\CMS\Core\Package\PackageManager::mapExtensionManagerConfigurationToComposerManifest() to read and parse ext_emconf.php files. The latter can throw some exceptions with details on what went wrong. These are caught inside getComposerManifest() and instead an exception is thrown that there is neither a composer.json nor an ext_emconf.php file found.

Example:
- remove version numbers in the conflict part of ext_emconf
- mapExtensionManagerConfigurationToComposerManifest throws an exception with the description "The extension "%s" has invalid version constraints in conflicts section. Extension key is missing!"
- getComposerManifest() catches this and throws the mysterious message "Neither a composer.json nor an ext_emconf.php file was found for extension <name>"