ValueError: Invalid control character at: line 1 column 351443 (char 351442)

Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/__main__.py", line 13, in <module>
    sys.exit(console_main())
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/main.py", line 51, in console_main
    return main(GrizzlyArgs().parse_args())
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/main.py", line 161, in main
    session.run()
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/session.py", line 196, in run
    self.check_results(not files_served, server_status == sapphire.SERVED_TIMEOUT)
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/session.py", line 56, in check_results
    self.report_result()
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/session.py", line 155, in report_result
    self.reporter.submit(result_logs, self.iomanager.tests)
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/common/reporter.py", line 254, in submit
    self._submit(report, test_cases)
  File "/home/worker/grizzly-auto-run/grizzly/grizzly/common/reporter.py", line 503, in _submit
    new_entry = collector.submit(crash_info, testCase=zip_name, testCaseQuality=self.quality)
  File "/home/worker/grizzly-auto-run/FuzzManager/Reporter/Reporter.py", line 43, in decorator
    return wrapped(self, *args, **kwargs)
  File "/home/worker/grizzly-auto-run/FuzzManager/Collector/Collector.py", line 153, in submit
    return self.post(url, data).json()
  File "/home/worker/grizzly-auto-run/venv/local/lib/python2.7/site-packages/requests/models.py", line 889, in json
    self.content.decode(encoding), **kwargs
  File "/usr/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 380, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Invalid control character at: line 1 column 351443 (char 351442)

Start with grizzly/common/reporter.py at _submit and FuzzManager/Collector/Collector.py at submit, then trace the response returned by self.post(url, data). Determine why the response cannot be decoded as JSON and define the expected behavior for this failure; the issue is complete when report submission handles this case reliably.