-handle case where channel is NULL (failed to be created?), see #3125

git-svn-id: https://gnunet.org/svn/gnunet@30884 140774ce-b5e7-0310-ab8b-a85725594a96
allow spaces in binary file names (#3094)

git-svn-id: https://gnunet.org/svn/gnunet@30885 140774ce-b5e7-0310-ab8b-a85725594a96