Check if there is any correct option for each question

gen.pl

@@ -31,7 +31,7 @@ sub md {    # pipe through $markdown
 sub add {
   return unless %last_option;
 
-  if (defined $last_option{"comment"}) {
+  if ($last_option{"comment"}) {
     $last_option{"comment"} = md($last_option{"comment"});
   }
   
@@ -44,9 +44,19 @@ while (<>) {
   } elsif (/^.$/) {
     add();
 
-    die "end of block without a question at line $.\n"
+    die "end of block without a question at line $ARGV:$.\n"
       unless defined $question;
 
+    my $any = 0;
+    foreach my $opt (@options) {
+      # unless (defined $opt->{"correct"}) {
+      # 	die "undefined \"$question\" ($ARGV:$.)\n";
+      # }
+      $any = 1 if (not (defined $opt->{"correct"})) or ($opt->{"correct"} eq JSON::true);
+    }
+    die "no correct option at \"$question\" ($ARGV)\n"
+      unless $any;
+
     my %ent =
       (
        "question" => md($question),