Fix iteration over undefined values

Allow for iteration on undefined values, but special case undefined and null to prevent rendering errors when not running in strict mode.

Fixes #1093

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/handlebars/compiler/javascript-compiler.js b/lib/handlebars/compiler/javascript-compiler.js
index d0f206c..bd48e9b 100644
--- a/lib/handlebars/compiler/javascript-compiler.js
+++ b/lib/handlebars/compiler/javascript-compiler.js
@@ -984,13 +984,14 @@ JavaScriptCompiler.prototype = {
   setupHelper: function(paramSize, name, blockHelper) {
     let params = [],
         paramsInit = this.setupHelperArgs(name, paramSize, params, blockHelper);
-    let foundHelper = this.nameLookup('helpers', name, 'helper');
+    let foundHelper = this.nameLookup('helpers', name, 'helper'),
+        callContext = this.aliasable(`${this.contextName(0)} != null ? ${this.contextName(0)} : {}`);
 
     return {
       params: params,
       paramsInit: paramsInit,
       name: foundHelper,
-      callParams: [this.contextName(0)].concat(params)
+      callParams: [callContext].concat(params)
     };
   },