Add error handling to synchronous methods (obligatory warning against using synchronous calls at all).

lib/web3/httpprovider.js

@@ -48,7 +48,16 @@ HttpProvider.prototype.send = function (payload) {
     //if (request.status !== 200) {
         //return;
     //}
-    return JSON.parse(request.responseText);
+
+    var result = request.responseText;
+
+    try {
+        result = JSON.parse(result);
+    } catch(e) {
+        throw errors.InvalidResponse(result);                
+    }
+
+    return result;
 };
 
 HttpProvider.prototype.sendAsync = function (payload, callback) {