toroplus appears to be one of the two CDMA variants of the Galaxy Nexus. The
ubuntu-system images currently only support the GSM variant of that handset (
maguro), which explains the error.
It looks like someone in the community ported one of the early phone images to
toroplus, but it doesn't look like it's been updated in about 8 months:
It also says that the actual phone functionality doesn't work on that image (an area where the CDMA version differs from the original GSM one). More information can be found in the forum thread on XDA Developers: