Domain-Mapping - Uninitialized string offset

I was having an issue with the Domain Mapping plugin and carried out the fix as per my post here:
https://premium.wpmudev.org/forums/topic/domain-mapping-plugindatabase-died-upon-deleting-existing-mapping#post-390803

Now, whenever I try to ADD a new Multi-Domain entry through the admin, I get a blank/half rendered page.

When I turn debugging on and try adding again, this is the error that shows on the multi-domains settings page:

Notice: Uninitialized string offset: 0 in E:\inetpub\vs239227\wp-content\mu-plugins\multi-domains.php on line 339

Fatal error: Cannot use string offset as an array in E:\inetpub\vs239227\wp-content\mu-plugins\multi-domains.php on line 339

Is there any possible way of clearing/resetting all multi-domains settings/entries in the database automatically?

Thanks, Kent