`_installModule` doesn't revert if module is already enabled, doesn't in compliance with ERC7579
GitHub
https://github.com/Cyfrin/2024-07-biconomy/blob/9590f25cd63f7ad2c54feb618036984774f3879d/contracts/Nexus.sol#L187-L190
Summary
The installModule function in Nexus.sol calls _installModule to add a new module to the smart account. However, _installModule lacks a check to revert if the module is already enabled. This violates the requirements of EIP-7579, which mandates reverting if the module is already enabled.
Impact
Without this check, the system allows redundant installations of modules, which can lead to potential security risks & unnecessary consumption of resources. This behavior does not comply with EIP-7579, potentially compromising the integrity of the modular smart account system.
Recommendation
Add a check in the _installModule function to verify if the module is already installed. If it is, revert the transaction to prevent redundant installations. Ensure that the ModuleAlreadyInstalled error is defined and used appropriately within the function.
Lead Judging Commences
finding-ERC7579-does-not-revert-when-module-installed
Invalid per comments [here](https://github.com/Cyfrin/2024-07-biconomy/blob/9590f25cd63f7ad2c54feb618036984774f3879d/contracts/base/ModuleManager.sol#L185-L186), with checks implemented [in this contract here](https://github.com/rhinestonewtf/sentinellist/blob/main/src/SentinelList.sol)
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