[widgets][editor] Show error message on new asset creation failure

For example, if a default Algorithm can't be constructed because the
prefix used lacks the reference datformats, show the exception message
rather than make the application crash.
2 jobs for implement_asset_creation in 21 minutes and 40 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #164806
docker-build
build_linux_36

00:05:36

passed #164807
macosx
build_macosx_36

00:21:40