Liwei apparently (years) ago reported a warning in TimerReport about it using &foo[0] even when foo is an empty vector.

Pull request https://bitbucket.org/cactuscode/cactusutils/pull-requests/47 addresses this.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2954/timerreport-contains-dodgy-code-if-there