Bug 356336: Crash when calling showdependencytree.cgi with no bug ID - Patch by Fr�d�ric Buclin <LpSolit@gmail.com> r=mkanat a=myk

webtools/bugzilla/showdependencytree.cgi

@@ -49,7 +49,7 @@ my $dbh = Bugzilla->switch_to_shadow_db();
 
 # Make sure the bug ID is a positive integer representing an existing
 # bug that the user is authorized to access.
-my $id = $cgi->param('id');
+my $id = $cgi->param('id') || ThrowUserError('invalid_bug_id_or_alias');
 ValidateBugID($id);
 my $current_bug = new Bugzilla::Bug($id);