Fix/allow registry to be zero address

[github-actions[bot]]

:robot: Slither Analysis Report :mag_right:

Slither report

# Slither report **THIS CHECKLIST IS NOT COMPLETE**. Use `--show-ignored-findings` to show all the results. Summary - [constable-states](#constable-states) (2 results) (Optimization) ## constable-states Impact: Optimization :red_circle: Confidence: High - [ ] ID-0 [RegistryAdapter.registry]([base/RegistryAdapter.sol#L10](https://github.com/bcnmy/nexus/blob/c1e212fbe98290171c3ee4dbe6bbdac4193619f0/contracts/contracts/base/RegistryAdapter.sol#L10)) should be constant [base/RegistryAdapter.sol#L10](https://github.com/bcnmy/nexus/blob/c1e212fbe98290171c3ee4dbe6bbdac4193619f0/contracts/contracts/base/RegistryAdapter.sol#L10) - [ ] ID-1 [RegistryFactory.threshold]([factory/RegistryFactory.sol#L39](https://github.com/bcnmy/nexus/blob/c1e212fbe98290171c3ee4dbe6bbdac4193619f0/contracts/contracts/factory/RegistryFactory.sol#L39)) should be constant [factory/RegistryFactory.sol#L39](https://github.com/bcnmy/nexus/blob/c1e212fbe98290171c3ee4dbe6bbdac4193619f0/contracts/contracts/factory/RegistryFactory.sol#L39)

This comment was automatically generated by the GitHub Actions workflow.

[github-actions[bot]]

Changes to gas cost

Generated at commit: c1e212fbe98290171c3ee4dbe6bbdac4193619f0, compared to commit: 67d48082fb317198353e7310af80ecd3d74474fc

🧾 Summary (5% most significant diffs)

Contract	Method	Avg (+/-)	%
Nexus	execute	+17,361 ❌	+54.86%
MockPaymaster	getHash	+41 ❌	+1.80%

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Full diff report 👇

| Contract | Deployment Cost (+/-) | Method | Min (+/-) | % | Avg (+/-) | % | Median (+/-) | % | Max (+/-) | % | # Calls (+/-) | |:-|-:|:-|-:|-:|-:|-:|-:|-:|-:|-:|-:| | **Nexus** | 5,641,328 (-158,392) | _execute_
_executeFromExecutor_
_initializeAccount_
_isModuleInstalled_
_validateUserOp_ | 6,175 (-22)
14,477 (-22)
111,052 (0)
611 (0)
7,142 (0) | **-0.36%**
**-0.15%**
**0.00%**
**0.00%**
**0.00%** | 49,006 (+17,361)
19,773 (-22)
130,887 (+15)
804 (-6)
8,713 (-29) | **+54.86%**
**-0.11%**
**+0.01%**
**-0.74%**
**-0.33%** | 37,875 (+1,249)
19,603 (-22)
130,952 (0)
780 (0)
7,142 (0) | **+3.41%**
**-0.11%**
**0.00%**
**0.00%**
**0.00%** | 142,953 (+95,013)
25,409 (-22)
130,952 (0)
2,839 (0)
35,933 (+119) | **+198.19%**
**-0.09%**
**0.00%**
**0.00%**
**+0.33%** | 76 (+13)
4 (0)
309 (+58)
331 (+58)
351 (+63) | | **MockPaymaster** | 1,161,593 (0) | _getHash_ | 2,087 (0) | **0.00%** | 2,318 (+41) | **+1.80%** | 2,427 (+152) | **+6.68%** | 2,697 (+233) | **+9.46%** | 17 (+5) | | **Bootstrap** | 2,552,273 (0) | _initNexusScoped_ | 62,207 (0) | **0.00%** | 82,042 (+15) | **+0.02%** | 82,107 (0) | **0.00%** | 82,107 (0) | **0.00%** | 309 (+58) |