Fetching nonce for a pristine account returns 0, which is erroneously translated as an error.

[bashlund]

Environment/Browser

Chromium

Description

In the Superprovider there is a function to fetch the nonce of the selected account.
If this is a new account the nonce is 0, and that is interpreted as an error since the if statement is vague.

const nonce = await this.getNonce(this.selectedEnvironment.endpoint, this.selectedAccount.address)
    .catch((err) => console.log(err));
    if (!nonce) {
        alert('The nonce could not be fetched');
        return;
    }

Steps to reproduce

1. Deploy a CryptoPizza template
2. Deploy using Default account
3. Switch to new pristine account
4. Create a new pizza
5. See the error alert popup.

Expected result

Nonce for pristine accounts are 0 and that should not be interpreted as an error.

Actual result

For pristine accounts the application fails posting a transaction from preview.

Reproducible

Yes, if using the fixed features where the correct account is set in the preview (#86)