HAR Export Timing out on certain websites

[codersbrew]

Firefox: 52.0.2
Latest Selenium
Python 2.7.X
Har Trigger Exporter beta 10

The basic flow, I run a python web driver headless firefox. In firefox I add the exporter extension and go to a website (http://nbcnews.com). I then call the async script below. Normally, the HAR is pushed to the directory I wanted and all is fine, but every so often the HAR trigger script will timeout and return an error of timedout and no HAR is generated. How do I debug the specific error using a headless firefox in python webdriver? Is it possible that firefox is failing? Anyway I can get more debug info?

`

        browser.get(url)
        browser.set_script_timeout(60)
        test = browser.execute_async_script("""
        var options  = {token: "test", fileName: "output"};
        var callback = arguments[arguments.length - 1];

        function triggerExport() {
          HAR.triggerExport(options).then(result => {
                                  callback("It worked");
                                }, err => {
                                  callback(err);
                                });
        };

        if (typeof HAR === 'undefined') {
          addEventListener('har-api-ready', triggerExport, false);
        } else {
          triggerExport();
        };
            """)  `

  Message: TypeError: file.requestHeaders is undefined
  Stack:
    HarBuilder.prototype.buildPostData@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-builder.js:252:7
HarBuilder.prototype.buildRequest@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-builder.js:176:24
HarBuilder.prototype.buildEntry@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-builder.js:128:21
HarBuilder.prototype.build@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-builder.js:66:24
HarExporter.buildHarData@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-exporter.js:166:12
HarExporter.fetchHarData@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-exporter.js:131:12
HarAutomation<.executeExport@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-automation.js:183:12
TriggerToolboxOverlay<.triggerExport@resource://gre/modules/commonjs/toolkit/loader.js -> resource://harexporttrigger-at-getfirebug-dot-com/lib/trigger-toolbox-overlay.js:253:5
emitOnObject@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/commonjs/sdk/event/core.js:112:9
emit@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/commonjs/sdk/event/core.js:89:38
Front<.onPacket@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/protocol.js:1258:7
DebuggerClient.prototype.onPacket@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/client/main.js:947:7
LocalDebuggerTransport.prototype.send/<@chrome://marionette/content/server.js -> resource://devtools/shared/transport/transport.js:570:13
exports.makeInfallible/<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/ThreadSafeDevToolsUtils.js:101:14
exports.makeInfallible/<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/ThreadSafeDevToolsUtils.js:101:14

*************************
A coding exception was thrown and uncaught in a Task.

Full message: TypeError: can't convert undefined to object
Full stack: exports.getFormDataSections<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/request-utils.js:56:7
TaskImpl.prototype._run@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/task.js:311:39
TaskImpl@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/task.js:273:3
createAsyncFunction/asyncFunction@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/task.js:247:14
HarBuilder.prototype.buildPostData/<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-builder.js:276:9
Handler.prototype.process@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:932:23
this.PromiseWalker.walkerLoop@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:813:7
this.PromiseWalker.scheduleWalkerLoop/<@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:747:11

*************************
*************************
A coding exception was thrown and uncaught in a Task.

Full message: TypeError: can't convert undefined to object
Full stack: exports.getFormDataSections<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/request-utils.js:56:7
TaskImpl.prototype._run@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/task.js:311:39
TaskImpl@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/task.js:273:3
createAsyncFunction/asyncFunction@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/task.js:247:14
HarBuilder.prototype.buildPostData/<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/client/netmonitor/har/har-builder.js:276:9
Handler.prototype.process@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:932:23
this.PromiseWalker.walkerLoop@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:813:7
this.PromiseWalker.scheduleWalkerLoop/<@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:747:11

`

[codersbrew]

Seems like this is the cause.

https://bugzilla.mozilla.org/show_bug.cgi?id=1383844