fix: don't throw when queryBy methods return null

Author: jrolfs

lib/fixture/locator.ts

@@ -74,10 +74,7 @@ const engine: () => SelectorEngine = () => ({
  // @ts-expect-error
  const result = testingLibrary[queryName](root, ...args)
 
- if (!result)
- throw new Error(
- `PlaywrightTestingLibrary: '${queryName}' was used to create this Locator and the query returned \`null\``,
- )
+ if (!result) return []
 
  return Array.isArray(result) ? result : [result]
  },