commands: Do not print error on missing unknown dirs
commands: Do not print error on missing unknown dirs

See #2602

digitalcraftsman/hugo,bogem/hugo,digitalcraftsman/hugo,gohugoio/hugo,fedelibre/hugo,mdhender/hugo,bogem/hugo,gohugoio/hugo,tubo028/hugo,gohugoio/hugo,mdhender/hugo,mdhender/hugo,MarkDBlackwell/hugo,fedelibre/hugo,mitchchn/hugo,anthonyfok/hugo,mayah/hugo,tubo028/hugo,jygastaud/hugo,mayah/hugo,fedelibre/hugo,anthonyfok/hugo,fedelibre/hugo,mitchchn/hugo,Zenithar/hugo,mdhender/hugo,jygastaud/hugo,MarkDBlackwell/hugo,anthonyfok/hugo,Zenithar/hugo