template_depends: throw nice error message when template cannot be found

plovs reported a crash when templates were not installed properly,
with a non-useful error about the template object not being defined.
I've audited all uses of template_depends(), and template(), and it makes
sense for them to throw an error if the template cannot be found. All code
with a user-supplied template catches errors already, to handle template
parse failures.

It did not make sense for template_file to throw errors, as some code uses
it to probe if a template file is available.

1 files changed, 5 insertions, 3 deletions

diff --git a/IkiWiki.pm b/IkiWiki.pm
index 6da281999..66ae86809 100644
--- a/IkiWiki.pm
+++ b/IkiWiki.pm
@@ -1769,12 +1769,14 @@ sub template_depends ($$;@) {
 	my $page=shift;
 	
 	my ($filename, $tpage, $untrusted)=template_file($name);
+	if (! defined $filename) {
+		error(sprintf(gettext("template %s not found"), $name))
+	}
+
 	if (defined $page && defined $tpage) {
 		add_depends($page, $tpage);
 	}
-
-	return unless defined $filename;
-
+	
 	my @opts=(
 		filter => sub {
 			my $text_ref = shift;