delete invalid code

[codecov[bot]]

Codecov Report

Base: 32.21% // Head: 32.64% // Increases project coverage by +0.42% :tada:

Coverage data is based on head (ce80777) compared to base (a7b0fc1). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev-3.0.0 #202 +/- ## ============================================= + Coverage 32.21% 32.64% +0.42% ============================================= Files 5 5 Lines 686 677 -9 ============================================= Hits 221 221 + Misses 412 403 -9 Partials 53 53 ``` | [Impacted Files](https://codecov.io/gh/FISCO-BCOS/go-sdk/pull/202?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FISCO-BCOS) | Coverage Δ | | |---|---|---| | [client/json.go](https://codecov.io/gh/FISCO-BCOS/go-sdk/pull/202?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FISCO-BCOS#diff-Y2xpZW50L2pzb24uZ28=) | `0.00% <ø> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FISCO-BCOS). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FISCO-BCOS)

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