Describe the bug:

occasionally raise Exception: too many values to unpack (expected 2) and 'NoneType' object is not iterable

To Reproduce

can not reproduce, it happen occasionally

Environment (please complete the following information)

• OS: Ubuntu 28.04

• Python version: 3.7.5

• Framework and version: flask 1.1.1 flask-sqlalchemy 2.3.2

• Agent version: 5.8.1

• Agent config options

  Click to expand

      ELASTIC_APM = {
          "SERVICE_NAME": f"we-work-server_{RUN_ENV}",
          "SERVER_URL": "",
          "ENABLED": True,
          "DISABLE_SEND: False,
          "RECORDING": True,
          "INSTRUMENT": True,
          "ENABLE_DISTRIBUTED_TRACING": True,
          "USE_ELASTIC_TRACEPARENT_HEADER": True,
          "CLOUD_PROVIDER": False,
          "INSTRUMENT_DJANGO_MIDDLEWARE": False,
          "AUTOINSERT_DJANGO_MIDDLEWARE": False,
          "SERVICE_VERSION": os.getenv("CODE_RELEASE_VERSION", None),
  }
  

• requirements.txt:

  Click to expand

      attrs==19.3.0
      celery==4.4.6
      certifi==2019.11.28
      cffi==1.13.2
      chardet==3.0.4
      crcmod==1.7
      cryptography==2.8
      flasgger==0.9.3
      Flask==1.1.1
      Flask-Redis==0.3.0
      Flask-SQLAlchemy==2.3.2
      greenlet==0.4.14
      idna==2.8
      importlib-metadata==1.2.0
      itsdangerous==1.1.0
      Jinja2==2.10.3
      jmespath==0.9.4
      jsonschema==2.6.0
      lxml==4.4.1
      MarkupSafe==1.1.1
      mistune==0.8.4
      more-itertools==8.0.1
      pybase64==1.0.1
      pycodestyle==2.5.0
      pycparser==2.19
      pycryptodome==3.8.2
      PyMySQL==0.8.1
      pyrsistent==0.15.6
      pytz==2019.3
      PyYAML==5.1.2
      redis==3.3.11
      six==1.13.0
      specs==0.0.0
      SQLAlchemy==1.2.8
      typing-extensions==3.7.4.1
      urllib3==1.25.7
      uWSGI==2.0.18
      vine==1.3.0
      Werkzeug==0.16.0
      xmltodict==0.11.0
      zipp==0.6.0
      xlrd==1.2.0
      pyzbar==0.1.8
      Pillow==7.1.1
      urlextract==0.14.0
      elastic-apm==5.8.1
      sentry-sdk[flask]==0.15.1
      arrow==0.16.0
      sqlparse==0.3.1
      elasticsearch==7.9.1
      pydantic==1.6.1
      apispec==3.3.2
      marshmallow==3.7.1
      python-socketio==4.6.0