Fix typecheck error: use non-null assertion after expect(pair).toBeDefined()

src/lib/theme-contrast.test.ts

@@ -171,7 +171,7 @@ describe("derivePublicForegrounds", () => {
 					);
 					expect(pair, `missing ${name}`).toBeDefined();
 					expect(
-						contrastRatio(pair?.foreground, pair?.background),
+						contrastRatio(pair!.foreground, pair!.background),
 						name,
 					).toBeGreaterThanOrEqual(4.5);
 				}