[BUGFIX] Throw Exception if typo3 extension repository is not defined

When there is no repository with id 1 is defined
in tx_extensionmanager_domain_model_extension you get an exception if
you try to update the extension list

Resolves: #42849
Releases: 6.1, 6.0
Change-Id: Ia60aa2227ab3a801c9002d821295c6eb01043e3f
Reviewed-on: https://review.typo3.org/19628
Reviewed-by: Nicole Cordes
Tested-by: Nicole Cordes
Reviewed-by: Sascha Egerer
Tested-by: Sascha Egerer
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn

typo3/sysext/extensionmanager/Classes/Utility/Repository/Helper.php

@@ -83,9 +83,12 @@ class Helper implements \TYPO3\CMS\Core\SingletonInterface {
 		$repositoryRepository = $this->objectManager->get('TYPO3\\CMS\\Extensionmanager\\Domain\\Repository\\RepositoryRepository');
 		$this->extensionRepository = $this->objectManager->get('TYPO3\\CMS\\Extensionmanager\\Domain\\Repository\\ExtensionRepository');
 		$repository = $repositoryRepository->findByUid(1);
-		if (is_object($repository)) {
-			$this->setRepository($repository);
+
+		if(!is_object($repository)) {
+			throw new \TYPO3\CMS\Extensionmanager\Exception\ExtensionManagerException('The typo3.org extension repository was not found. Please go to the "Update Wizard" in the install tool and run the task "Add the default Extension Manager database tables".', 1365192900);
 		}
+
+		$this->setRepository($repository);
 	}
 
 	/**

typo3/sysext/extensionmanager/Resources/Private/Language/locallang.xlf

@@ -325,7 +325,7 @@
 				<source>Error</source>
 			</trans-unit>
 			<trans-unit id="report.status.mainRepository.notFound.message" xml:space="preserve">
-				<source>The typo3.org extension repository was not found. Please import the main typo3.org extension repository in the install tool wizard.</source>
+				<source>The typo3.org extension repository was not found. Please go to the "Update Wizard" in the install tool and run the task "Add the default Extension Manager database tables".</source>
 			</trans-unit>
 			<trans-unit id="report.status.mainRepository.notUpToDate.value" xml:space="preserve">
 				<source>Extension list is not up to date!</source>