Reports fail when one data point fails
Line items should not fail when only a single data point fails. That is, a report should be robust enough to generate whatever details it can for each line item and provide an error at the cell level rather than the whole row. For example, I ran a Site Report and due to some corruption in the configuration of the site collection it threw a lot of errors stating "Unable to recover storage metrics for address '...'. It may no longer exist or you may not have the necessary permissions." However, when I run a custom report taking our the Size column, it runs fine.