Nicer error message when activating nonexistent rule (#246)

markdownlint · Oct 20, 2019 · 672496b · 672496b
1 parent 30a6951
commit 672496b
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/lib/mdl/style.rb b/lib/mdl/style.rb
@@ -25,7 +25,13 @@ def all
     end
 
     def rule(id, params={})
+      if block_given?
+        raise "'rule' does not take a block. Should this definition go in a ruleset instead?"
+      end
       id = @aliases[id] if @aliases[id]
+      unless @all_rules[id]
+        raise "No such rule: #{id}"
+      end
       @rules << id
       @all_rules[id].params(params)
     end