Better error should be shown when Namecoin Core is still syncing #90
Description
Namecoin Core gives this error when name_show is issued during syncup, so that the user doesn't unexpectedly get old data:
Namecoin is downloading blocks... (code -10)
Unfortunately NMControl isn't aware of this error (it doesn't happen in NamecoinQ), which causes getValue to return False, which isn't a useful error, particularly since a nonexistent name will also (I think) return False.
I suggest raising an exception in the namecoin and rest backends when this is encountered, so that NMControl returns the exception.
--- Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/24805787-better-error-should-be-shown-when-namecoin-core-is-still-syncing?utm_campaign=plugin&utm_content=tracker%2F435873&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F435873&utm_medium=issues&utm_source=github).