Fix REST JS client error hander callback code. Fixes #1680.
Fix REST JS client error hander callback code. Fixes #1680.

chalucha/vibe.d,DBankov/vibe.d,etcimon/vibe.d,rejectedsoftware/vibe.d,Geod24/vibe.d,gedaiu/vibe.d,etcimon/vibe.d