Fix #5190: Endless loop in muse style-run-hooks when muse-project-publish is called with undefined style.
* lisp/muse-project.el (muse-project-publish): If we cannot find a
project to publish, indicate this in an error message.
* lisp/muse-publish.el (muse-style-run-hooks): Never go into an endless
loop. This should fix #5190. Thanks to Rod Morehead for the report.
(muse-detect-invalid-style): New function that makes sure that the
given style is in a valid format.
(muse-publish-file): Call `muse-detect-invalid-style' before doing any
publishing.
git-archimport-id: mwolson@gnu.org--2006/muse--main--1.0--patch-70