Add array validator

Author: ezewer

lib/validators/array.js

@@ -0,0 +1,12 @@
+'use strict'
+
+/**
+ * Validates a bool
+ *
+ * @param {*} v - value
+ * @returns {string} error - null if valid
+ */
+module.exports = (v) => (!Array.isArray(v)
+  ? 'must be an array'
+  : null
+)