We're aware of this issue and apologize for the inconvenience. We're looking into the issue on our side and hope to find a fix as soon as possible.
Please make sure you are using the latest version of Safari. You can download the latest version here: https://support.apple.com/en-us/HT204416
If you are already using the latest version of Safari, we recommend that in the meantime you try using another browser, such as Firefox or Google Chrome. We've had no reports of this same error happening with other browsers.