bug #3961 Throws proper Twig exception when using cycle on an empty array (fabpot)

This PR was merged into the 3.x branch.

Discussion
----------

Throws proper Twig exception when using cycle on an empty array

Closes #3925

Commits
-------

d21666f7 Throws proper Twig exception when using cycle on an empty array

src/Extension/CoreExtension.php

@@ -329,6 +329,10 @@ final class CoreExtension extends AbstractExtension
             return $values;
         }
 
+        if (!\count($values)) {
+            throw new RuntimeError('The "cycle" function does not work on empty arrays');
+        }
+
         return $values[$position % \count($values)];
     }
 

tests/Fixtures/functions/cycle_empty.test

@@ -0,0 +1,8 @@
+--TEST--
+"cycle" function returns an error on empty arrays
+--TEMPLATE--
+{{ cycle([], 0) }}
+--DATA--
+return []
+--EXCEPTION--
+Twig\Error\RuntimeError: The "cycle" function does not work on empty arrays in "index.twig" at line 2