(In reply to Mike Hommey [:glandium] from comment #8)
> Now, for this specific case, I'd advise removing the import feature instead
> of having weird errors when Firefox doesn't have the corresponding key.
I agree that the current behavior isn't okay. I've opened a bug to do something better, with room to discuss what "better" looks like (Bug 1110508)
(In reply to Mike Hommey [:glandium] from comment #8)
> Now, for this specific case, I'd advise removing the import feature instead
> of having weird errors when Firefox doesn't have the corresponding key.
I agree that the current behavior isn't okay. I've opened a bug to do something better, with room to discuss what "better" looks like (Bug 1110508)