[vector] Error message in the fromArray length check is misleading

[John Rose]

On Jan 30, 2019, at 2:09 PM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:
> 
> So, I'm in favor of improving error message itself leaving the check as is for now.
> 

This occasion was anticipated in the design of the Preconditions API.
You can plug in your own error reporter as a lambda, without abandoning
the intrinsic behavior.