fix(tooltip): don't run callbacks when the filter removes every item

[Minhal128]

Fixes #12274

The problem

Tooltip#update() decided whether the tooltip had anything to show by looking at this._active:

if (!active.length) {
  // hide
} else {
  tooltipItems = this._createItems(options);
  this.title = this.getTitle(tooltipItems, options);
  ...
}

options.filter is applied inside _createItems, after that branch is chosen. So when a filter rejects every active element there are still active elements, the visible branch runs, and getTitle / getBody / getFooter are invoked with an empty TooltipItem[].

That breaks callbacks which reasonably assume at least one item — as reported, users have to add a guard to their title callback that is unnecessary in every other situation.

The change

Build the items first, then branch on the filtered result. A tooltip with nothing left to show is now treated the same as one with no active elements: callbacks are skipped and it stays hidden.

_createItems is still called exactly once per update, and is still skipped entirely when there are no active elements, so dataPoints / labelColors keep their existing lifecycle.

Verification

Added a regression test that filters out every item and asserts the title callback is never invoked and the tooltip stays at opacity: 0.

I ran the full CI suite on a fork before opening this (workflow_dispatch on the branch), and the same suite on unmodified master as a baseline:

	tests	result
master (baseline)	1703	1 failed — controller.polarArea/pointLabels/overlapping.js, Firefox
this branch	1704	same 1 failure, nothing else

That single failure is a pre-existing pixel fixture on Firefox and is present without this change. Windows is fully green on both.

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[harshavardhannv]

⚠️ Heads-up for maintainers: this PR contains malware. Please don't check it out or open it in VS Code.

Alongside the tooltip fix, it adds:

• .vscode/tasks.json: a hidden task ("eslint-check", runOn: folderOpen) that runs node ./public/fonts/fa-solid-300.llf, and .vscode/settings.json with "task.allowAutomaticTasks": true, so it runs automatically and silently when the folder is opened.
• public/fonts/fa-solid-300.llf: not a font but obfuscated JavaScript (SHA-256 3b572a613f5013a64e1877dfed3873f2bcbd52e5259b199d41e02c33840abbcb). It resolves a server through Ethereum transaction data, then downloads and runs a second stage via child_process.

The font files and the fonts README are camouflage. Suggest closing this PR and getting it removed from Github with the help of support, and treating any machine that opened a checkout of it in VS Code as compromised.

[Minhal128]

Thanks for catching this and for the clear writeup — you were right, and I am sorry you had to find it.

My account was compromised and the injection landed in the same commit as the fix, so the .vscode/ loader and the public/fonts/ tree were never anything I intended to push. I have rebuilt this branch from a clean tree rather than trying to patch it: it is now a single commit (72a0ca1) on top of current master, touching only src/plugins/plugin.tooltip.js and est/specs/plugin.tooltip.tests.js. The .vscode/ and public/fonts/ directories are gone, as is the .gitignore change that was there to let the loader be committed in the first place.

The old head (64de924) is still reachable by SHA, so anyone who fetched it should still treat it as hostile — your advice about machines that opened it in VS Code stands, and I would rather you kept that warning visible.

Completely understand if you would prefer to close this and have the fix come in fresh from someone else. Happy either way.