Solution to jQuery error: “this.empty is not a function”

A few days ago I was working on a quite complex editor written almost entirely in JavaScript using jQuery library. At some point I noticed a weird error in Firefox error console: "this.empty is not a function".
The error description is quite confusing so it took a few seconds to realize what's wrong...

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Source: http://de77.com/javascript/solution-to-jquery-error-this-empty-is-not-a-function