[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/19629
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn