swapOwner can fail in CPKFactory

[hexyls]

If the estimated gas for createProxyAndExecTransaction is too low swapOwner can fail silently during execTransaction to Gnosis Safe v1.2.0 while not rolling back the whole transaction.

Users can potentially lose funds if they transfer assets to the proxy and ownership of the proxy is not successfully assigned to the user.

Transfer of ownership is not verified after the swapOwner call. We should probably check the return value of execTransaction to check if the transaction was successful.

example transaction

Should be considered for #126

[cag]

Closing this as this is a duplicate of #90

Edit: though admittedly this issue was described much better than the original 😅