Use generic.index if no endpoint available
Use generic.index if no endpoint available

During error handling, no endpoint is available. Fall back to the main index
endpoint in this case.

Fixes #355

MarauderXtreme/sipa,agdsn/sipa,lukasjuhrich/sipa,agdsn/sipa,lukasjuhrich/sipa,MarauderXtreme/sipa,lukasjuhrich/sipa,MarauderXtreme/sipa,agdsn/sipa,lukasjuhrich/sipa,agdsn/sipa