Support error code

Author: Daniel Brain

src/drivers/receive/types.js

@@ -79,11 +79,14 @@ export let RECEIVE_MESSAGE_TYPES = {
             }, err => {
 
                 let error = stringifyError(err).replace(/^Error: /, '');
+                // $FlowFixMe
+                let code = err.code;
 
                 return respond({
                     type: CONSTANTS.POST_MESSAGE_TYPE.RESPONSE,
                     ack: CONSTANTS.POST_MESSAGE_ACK.ERROR,
-                    error
+                    error,
+                    code
                 });
             })
 
@@ -116,7 +119,12 @@ export let RECEIVE_MESSAGE_TYPES = {
         deleteResponseListener(message.hash);
 
         if (message.ack === CONSTANTS.POST_MESSAGE_ACK.ERROR) {
-            return options.respond(new Error(message.error), null);
+            let err = new Error(message.error);
+            if (message.code) {
+                // $FlowFixMe
+                err.code = message.code;
+            }
+            return options.respond(err, null);
         } else if (message.ack === CONSTANTS.POST_MESSAGE_ACK.SUCCESS) {
             let data = message.data || message.response;
 

src/lib/serialize.js

@@ -85,7 +85,9 @@ type SerializedError = {
 function serializeError(err : mixed) : SerializedError {
     return {
         __type__: CONSTANTS.SERIALIZATION_TYPES.ERROR,
-        __message__: stringifyError(err)
+        __message__: stringifyError(err),
+        // $FlowFixMe
+        __code__: err.code
     };
 }
 
@@ -177,7 +179,12 @@ export function deserializeMethod(source : CrossDomainWindowType, origin : strin
 }
 
 export function deserializeError(source : CrossDomainWindowType, origin : string, obj : Object) : Error {
-    return new Error(obj.__message__);
+    let err = new Error(obj.__message__);
+    if (obj.__code__) {
+        // $FlowFixMe
+        err.code = obj.__code__;
+    }
+    return err;
 }
 
 export function deserializeZalgoPromise(source : CrossDomainWindowType, origin : string, prom : Object) : ZalgoPromise<mixed> {