return empty string when querying first letter of a list

1 files changed, 4 insertions, 1 deletions

diff --git a/threads.js b/threads.js
index 6ba0442..47d5616 100644
--- a/threads.js
+++ b/threads.js
@@ -83,7 +83,7 @@ ArgLabelMorph, localize, XML_Element, hex_sha512*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.threads = '2015-April-15';
+modules.threads = '2015-May-01';
 
 var ThreadManager;
 var Process;
@@ -2204,6 +2204,9 @@ Process.prototype.reportJoinWords = function (aList) {
 // Process string ops
 
 Process.prototype.reportLetter = function (idx, string) {
+    if (string instanceof List) { // catch a common user error
+        return '';
+    }
     var i = +(idx || 0),
         str = (string || '').toString();
     return str[i - 1] || '';