_rpc function cannot return generics

[DiamondJoseph]

To replicate, check out main and run blueapi serve then from the gui, use get_plans or get_devices. get_plans/plan_name works fine, as does get_devices/device_name, but the methods that return a list throw an exception during the _rpc method.

INFO:     127.0.0.1:52726 - "GET /devices HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 108, in __call__
    response = await self.dispatch_func(request, call_next)
  File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/main.py", line 343, in add_api_version_header
    response = await call_next(request)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 84, in call_next
    raise app_exc
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 70, in coro
    await self.app(scope, receive_or_disconnect, send_no_error)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
    raise exc
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
    await self.app(scope, receive, sender)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 20, in __call__
    raise e
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 17, in __call__
    await self.app(scope, receive, send)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/routing.py", line 718, in __call__
    await route.handle(scope, receive, send)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/routing.py", line 276, in handle
    await self.app(scope, receive, send)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/routing.py", line 66, in app
    response = await func(request)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/routing.py", line 241, in app
    raw_response = await run_endpoint_function(
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/routing.py", line 169, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/concurrency.py", line 41, in run_in_threadpool
    return await anyio.to_thread.run_sync(func, *args)
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/to_thread.py", line 56, in run_sync
    return await get_async_backend().run_sync_in_worker_thread(
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2177, in run_sync_in_worker_thread
    return await future
  File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 859, in run
    result = context.run(func, *args)
  File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/main.py", line 126, in get_devices
    return DeviceResponse(devices=runner.run(interface.get_devices))
  File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/runner.py", line 89, in run
    return self._run_in_subprocess(function, *args, **kwargs)
  File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/runner.py", line 110, in _run_in_subprocess
    return self._subprocess.apply(
  File "/usr/lib/python3.10/multiprocessing/pool.py", line 360, in apply
    return self.apply_async(func, args, kwds).get()
  File "/usr/lib/python3.10/multiprocessing/pool.py", line 774, in get
    raise self._value
TypeError: isinstance() argument 2 cannot be a parameterized generic

During handling of the above exception, another exception occurred:

  + Exception Group Traceback (most recent call last):
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/uvicorn/protocols/http/httptools_impl.py", line 399, in run_asgi
  |     result = await app(  # type: ignore[func-returns-value]
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/uvicorn/middleware/proxy_headers.py", line 70, in __call__
  |     return await self.app(scope, receive, send)
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/applications.py", line 290, in __call__
  |     await super().__call__(scope, receive, send)
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/applications.py", line 122, in __call__
  |     await self.middleware_stack(scope, receive, send)
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/errors.py", line 184, in __call__
  |     raise exc
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/errors.py", line 162, in __call__
  |     await self.app(scope, receive, _send)
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 106, in __call__
  |     async with anyio.create_task_group() as task_group:
  |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 680, in __aexit__
  |     raise BaseExceptionGroup(
  | exceptiongroup.ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
    | multiprocessing.pool.RemoteTraceback: 
    | """
    | Traceback (most recent call last):
    |   File "/usr/lib/python3.10/multiprocessing/pool.py", line 125, in worker
    |     result = (True, func(*args, **kwds))
    |   File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/runner.py", line 146, in _rpc
    |     if expected_type is None or isinstance(value, expected_type):
    | TypeError: isinstance() argument 2 cannot be a parameterized generic
    | """
    | 
    | The above exception was the direct cause of the following exception:
    | 
    | Traceback (most recent call last):
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 108, in __call__
    |     response = await self.dispatch_func(request, call_next)
    |   File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/main.py", line 343, in add_api_version_header
    |     response = await call_next(request)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 84, in call_next
    |     raise app_exc
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/base.py", line 70, in coro
    |     await self.app(scope, receive_or_disconnect, send_no_error)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
    |     raise exc
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
    |     await self.app(scope, receive, sender)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 20, in __call__
    |     raise e
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 17, in __call__
    |     await self.app(scope, receive, send)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/routing.py", line 718, in __call__
    |     await route.handle(scope, receive, send)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/routing.py", line 276, in handle
    |     await self.app(scope, receive, send)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/routing.py", line 66, in app
    |     response = await func(request)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/routing.py", line 241, in app
    |     raw_response = await run_endpoint_function(
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/fastapi/routing.py", line 169, in run_endpoint_function
    |     return await run_in_threadpool(dependant.call, **values)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/starlette/concurrency.py", line 41, in run_in_threadpool
    |     return await anyio.to_thread.run_sync(func, *args)
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/to_thread.py", line 56, in run_sync
    |     return await get_async_backend().run_sync_in_worker_thread(
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2177, in run_sync_in_worker_thread
    |     return await future
    |   File "/home/qwe67581/Documents/work/blueapi/venv/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 859, in run
    |     result = context.run(func, *args)
    |   File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/main.py", line 126, in get_devices
    |     return DeviceResponse(devices=runner.run(interface.get_devices))
    |   File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/runner.py", line 89, in run
    |     return self._run_in_subprocess(function, *args, **kwargs)
    |   File "/home/qwe67581/Documents/work/blueapi/src/blueapi/service/runner.py", line 110, in _run_in_subprocess
    |     return self._subprocess.apply(
    |   File "/usr/lib/python3.10/multiprocessing/pool.py", line 360, in apply
    |     return self.apply_async(func, args, kwds).get()
    |   File "/usr/lib/python3.10/multiprocessing/pool.py", line 774, in get
    |     raise self._value
    | TypeError: isinstance() argument 2 cannot be a parameterized generic
    +------------------------------------
INFO:     127.0.0.1:48068 - "GET /devices/foo HTTP/1.1" 404 Not Found
INFO:     127.0.0.1:37548 - "GET /devices/sample_pressure HTTP/1.1" 200 OK