Explanation:

Here’s the thing—let’s break down each segment:

- Option 1: "I wish"

- Totally fine. It’s setting up a hypothetical, expressing regret.

- Option 2: "I have worked"

- This is the issue. After “I wish,” we use the past perfect: “I had worked,” not “I have worked.” That’s the right grammar for wishes about the past.

- Option 3: "harder than I did"

- No problem here. It’s comparing effort, which fits the sentence.

- Option 4: "No error"

- Not right, because there *is* an error.

So, your answer, Option 2, is correct.