Fix wrong condition on staff

jm2l/templates/NewIndex.mako

@@ -23,7 +23,7 @@
 <H2 style="text-align: center;" class="shadow">${edition | n} édition des JM2L en ${year}</H2>
 <br>
 <center>
-% if request.user.Staff:
+% if request.user and request.user.Staff:
     <a href="/${year or 2015}/edit">Editer cette page</a> -
 % endif
     <a href="/${year or 2015}/le-programme">Le programme des évenements ${year or 2015 }</a>