modeline: Fix an error about matching non-strings

* modeline.el (modeline-length): I was matching a variable whose can
  be nil. Check if it is a string before matching solves the potential
  problem.

Also remove two files that need not be under version-control.

1 files changed, 11 insertions, 14 deletions

diff --git a/recentf b/recentf
index 8445583..d4a2263 100644
--- a/recentf
+++ b/recentf
@@ -1,26 +1,23 @@
-;;; Automatically generated by ‘recentf’ on Mon Mar 15 15:34:08 2021.
+;;; Automatically generated by ‘recentf’ on Sun May 16 18:38:08 2021.
 
 (setq recentf-list
       '(
+        "/Users/durand/org/notes(1).org_archive"
         "/Users/durand/.emacs.d/bookmarks"
-        "/Users/durand/org/math_article_links.org"
         "/Users/durand/org/aujourdhui.org"
+        "/Users/durand/org/math_article_links.org"
         "/Users/durand/org/agenda.org"
         "/Users/durand/org/notes.org"
-        "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/exercise.synctex.gz"
-        "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/exercise.tex"
-        "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/exercise.pdf"
-        "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/notes.pdf"
-        "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/notes.synctex.gz"
-        "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/notes.tex"
         "/Users/durand/.newsrc.eld"
-        "/Users/durand/romans/輪回樂園/contents.html"
-        "/Users/durand/romans/輪回樂園/contents"
-        "/Users/durand/Downloads/documents intéressants/Théorie de nombres/Equations over Finite Fields An Elementary Approach by Wolfgang M. Schmidt (auth.) (z-lib.org).pdf"
-        "/Users/durand/Desktop/Centre/Mes notes/Les Notes/post stamp problem/poststamp.pdf"
-        "/Users/durand/Desktop/Centre/Mes notes/Les Notes/post stamp problem/poststamp.synctex.gz"
-        "/Users/durand/Desktop/Centre/Mes notes/Les Notes/post stamp problem/poststamp.tex"
+        "/Users/durand/Desktop/Centre/PDF/textbooks/Abstract Algebra, 3rd Edition by David S. Dummit, Richard M. Foote (z-lib.org).pdf"
+        "/Users/durand/.emacs.d/view-conf.el"
+        "/Users/durand/Desktop/Centre/PDF/American Mathematical Monthly/On Gauss First Proof of the Fundamental Theorem of Algebra.pdf"
+        "/Users/durand/Desktop/Centre/PDF/American Mathematical Monthly/Exponentials reiterated by Arthur Knoebel.pdf"
+        "/Users/durand/Desktop/Centre/Mes notes/Devoirs et classes/Autres/MaoBaoBao/order of product.pdf"
+        "/Users/durand/Desktop/Centre/PDF/Pas encore lu/lectures on derived categories.pdf"
         "/Users/durand/Desktop/Centre/Mes notes/Iwasawa theory/Iwasawa Theory.pdf"
+        "/Users/durand/Desktop/Centre/Tibetan/exercise.txt"
+        "/Users/durand/Desktop/Centre/Tibetan/exercise.pages"
         ))
 
 (setq recentf-filter-changer-current 'nil)