commands: Make sure build error is logged in watch mode
commands: Make sure build error is logged in watch mode

See #3062

mitchchn/hugo,mdhender/hugo,gohugoio/hugo,digitalcraftsman/hugo,anthonyfok/hugo,fedelibre/hugo,anthonyfok/hugo,fedelibre/hugo,fedelibre/hugo,gohugoio/hugo,mdhender/hugo,gohugoio/hugo,mdhender/hugo,fedelibre/hugo,mitchchn/hugo,digitalcraftsman/hugo,mdhender/hugo,anthonyfok/hugo