When we write code, we have certain assumptions. Most of these times, these assumptions are fine, and allow us to skip past some hard decisions. But sometimes, these can lead to problems. The infamous example would be the Y2K problem- the assumption that nobody'd be running this program in 40 years seemed reasonable at the time. We might assume that nobody'd type too fast. We might assume our sensor is accurate.
Darren sends us some code that has a much milder assumption than those:
Assert(false, 'Contact ANTHONY if you get this error');
The assumption here was that Anthony's employment would last longer than this code did. That was not true. It's legacy code, so there's no meaningful commit history that far back, there's no documentation or comments, and no one now at the company ever remembers an Anthony working there. No one knows why this error needs Anthony, no one knows what Anthony would do if this error was brought to his attention, and no one knows when the last time this error happened anyway.
To poetically paraphrase:
And in the codebase, these words appear:
"Contact ANTHONY if you get this error"
Nothing beside remains.