"No link definition found" for footnotes

When I use footnotes^fn1, the language server generates a warning.

Here’s a repro, put this is src/test/diagnostic.test.ts:

	test('Should not generate diagnostic for valid footnotes', withStore(async (store) => {
		const doc = new InMemoryDocument(workspacePath('doc.test.md'), joinLines(
			`footnotes should work[^fn1]`,
			``,
			`[^fn1]: this is a footnote`,
		));

		const workspace = store.add(new InMemoryWorkspace([doc]));

		const diagnostics = await getComputedDiagnostics(store, doc, workspace);
		assertDiagnosticsEqual(diagnostics, []);
	}));