Finite $L^1$ norm forces an integrable function to be finite almost everywhere.Suggest a slogan
Let \(m\) be Lebesgue measure on \(\RR^n\) and let \(f\colon\RR^n\to[-\infty,\infty]\) be measurable with \(\int_{\RR^n}\abs{f}\,dm<\infty\). Then \(m\qty{\theset{x\in\RR^n\suchthat \abs{f(x)} = \infty}} = 0\).