return early if Vector object creation or update errors
Merge pull request #93 from mapbox/return-vector-errors

return early if Vector object creation or update errors
Merge branch 'master' into tilelive-vector-030
Revert "switch tilelive-vector to 0.3.x"

This reverts commit 94c7e66e2cb508d938532519b581f5c1e52e029a.