A single line of JavaScript in this site's theme called a jQuery plugin that was never actually loaded, on every single page view, for just over ten months. Nobody was looking for it. It got deleted as a side effect of someone else's unrelated fix.
What the line did
js/custom.js opened with a call to initialize the Slick carousel plugin against any element matching .slick .view-content: responsive breakpoints, arrows, the works — a full, deliberately-configured options object, not a leftover stub. It was there in the theme's very first commit, cb49eeb, dated 2025-10-14.
What was missing
Nowhere in the theme's library definitions — checked across every .yml file, no matches at all for "slick" — is the actual Slick plugin ever attached, loaded from a CDN, or vendored in. The initialization call had a target and a configuration, but no library behind it. Every page load that reached that line of custom.js hit $(...).slick is not a function, because .slick() was never a real method on any jQuery object on this site. Not a rare edge case — this ran unconditionally, on load, on every page.
Ten months in a console nobody was watching
A thrown JavaScript error in a page-load script doesn't stop the page from rendering. It doesn't show up in server logs, doesn't fail a build, doesn't break anything a visitor would notice by looking at the page. It just sits in the browser console, silently, waiting for someone to actually open dev tools on this specific site and look. Between the theme's creation and 2026-08-29, apparently nobody did — or if they did, it didn't register as worth fixing over whatever else was in front of them that day.
How it actually got found
It wasn't found by an audit of this file, or a deliberate search for dead code. Commit 6de923a removes the entire Slick block in the middle of an unrelated theme-cleanup pass, with a commit message that names the actual symptom directly: "Slick plugin is not loaded, causing 'Uncaught TypeError: $(...).slick is not a function'." Whoever wrote that commit was almost certainly looking at the browser console for a different reason — the same session was chasing several other JS issues that day — and ran into this one along the way. The fix that mattered to that session was probably something else entirely; this got cleaned up because it was sitting right there in the same file.
The part worth remembering
Ten months is a long time for a guaranteed, unconditional error to go unaddressed on every page load of a live site. It's not evidence that the error was harmless — a broken carousel would matter if anyone had ever actually tried to use .slick markup on this site, and the fact that nobody complained says more about the markup never being used than about the error being safe to ignore. It's evidence about visibility: nothing about normal site operation — page loads succeeding, forms submitting, content publishing on schedule — would ever surface a console-only error, no matter how consistently it fires. The dead call didn't get fixed because it was a low priority. It got fixed because someone happened to be looking at exactly the right output, for an unrelated reason, on exactly the right day.