From bug 1706548, comment 2:

(In reply to Jens Stutte [:jstutte] from comment #1)

Looking at the translation of the error message vs. the place we generate it here I see a semantical mismatch between the two.

According to the original error definition I'd say, the translation "Component is not available" is questionable. (The widespread use of such an unspecific "Something not available" might be questionable, too, but a misleading message is probably worse than a generic one.)

Note that the translation appears to exist twice, see domerr.ms and xpc.msg.