Crash on starlette middleware in mount endpoints (StaticFiles)

Describe the bug: Elastic middleware crash on access to static files

Environment (please complete the following information)

• OS: [e.g. Linux]
• Python version: 3.9.4
• Framework and version [e.g. Django 2.1]: FastAPI
• APM Server version: 7.12.1
• Agent version: 7.12.1

from __future__ import annotations

import uvicorn
from elasticapm.contrib.starlette import ElasticAPM, make_apm_client
from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles

app = FastAPI(routes=[])
apm_config = {
    "SERVICE_NAME": "testing",
    "ENABLED": True,
    "SERVER_URL": "http://localhost:8200",
    "CAPTURE_HEADERS": True,
    "CAPTURE_BODY": "all",
}
apm = make_apm_client(apm_config)
app.add_middleware(ElasticAPM, client=apm)
app.mount("/static",StaticFiles(directory="/"),name="static")


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", debug=False)

The issue is happens when elastic running the function _get_route_name. the middleware will try to loop over the routes where starlette will return None in some cases:

  File "/home/syniex/.local/lib/python3.9/site-packages/elasticapm/contrib/starlette/__init__.py", line 233, in _get_route_name
    for route in routes:
                 └ None

TypeError: 'NoneType' object is not iterable

Starlette code that makes the issue:

@property
    def routes(self) -> typing.List[BaseRoute]:
        return getattr(self.app, "routes", None)

[basepi]

The PR is waiting on me. We have some upstream test failures caused by the new version of aiopg, which I’m working to fix here: https://github.com/elastic/apm-agent-python/pull/1178

Once that’s merged we should be able to get #1137 passing and merged. Thanks for your patience.

[bvader]

Hiya, @Sparkycz Any Updates on this? I have a customer eagerly awaiting this as well…the PR seems stalled?