Missing initializer guard in `_init()` function

The internal function _init within ERC721WithURIBuilderUpgradeable.sol lacks the onlyInitializing modifier. This function is called by the initializer function (init) of the upgradeable implementation contract PositionsManager.sol.

While the main PositionsManager.init function is protected by the initializer modifier, and the underlying __ERC721_init called by _init also has protection, the absence of the guard on _init itself poses a latent risk. If future upgrades to PositionsManager were to introduce new functions that mistakenly call _init again after initial deployment, there would be no direct protection at the _init level to prevent this call attempt.

Recommendation:

Add the onlyInitializing modifier to the ERC721WithURIBuilderUpgradeable._init function to explicitly enforce its initialization-only context and adhere to standard upgradeable contract patterns.

    function _init(string memory name_, string memory symbol_) internal onlyInitializing {
        __ERC721_init(name_, symbol_);
    }