Withdraw OverCollaterlized asset

withdrawCollateral is used in withdrawing an overcollaterlized asset from the protocol.

function withdrawCollateral(MarketParams memory marketParams, uint256 assets, address onBehalf, address receiver)
        external
    {
        Id id = marketParams.id();
        require(market[id].lastUpdate != 0, ErrorsLib.MARKET_NOT_CREATED);
        require(assets != 0, ErrorsLib.ZERO_ASSETS);
        require(receiver != address(0), ErrorsLib.ZERO_ADDRESS);
        // No need to verify that onBehalf != address(0) thanks to the following authorization check.
        require(_isSenderAuthorized(onBehalf), ErrorsLib.UNAUTHORIZED);

        _accrueInterest(marketParams, id);

        position[id][onBehalf].collateral -= assets.toUint128();

        require(_isHealthy(marketParams, id, onBehalf), ErrorsLib.INSUFFICIENT_COLLATERAL);

        emit EventsLib.WithdrawCollateral(id, msg.sender, onBehalf, receiver, assets);

        IERC20(marketParams.collateralToken).safeTransfer(receiver, assets);
    }