update_resource returns 500 error when absolute url is external

[Reinaard]

Describe the bug, issue or concern

A clear and concise description of what the bug, issue or concern is is.

E.g.

To Reproduce

1. Go to FHIR store and update Organization by changing the reference Endpoint/default-2 with PUT like this:

{
  "resourceType": "Organization",
  "id": "default-3",
  "endpoint": [
    {
      "reference": "http://some.server:9504/fhir/Endpoint/default-2"
    }
  ]
}

2. Go to mcsd-update-client and update resource
3. The following 500 internal server error appears:

INFO:     185.93.2.245:60473 - "POST /update_resources HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/fastapi/applications.py", line 1134, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/applications.py", line 113, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.11/site-packages/opentelemetry/instrumentation/asgi/__init__.py", line 743, in __call__
    await self.app(scope, otel_receive, otel_send)
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/exceptions.py", line 63, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.11/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 716, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 736, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 290, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/fastapi/routing.py", line 125, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.11/site-packages/fastapi/routing.py", line 111, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/fastapi/routing.py", line 391, in app
    raw_response = await run_endpoint_function(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/fastapi/routing.py", line 292, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/starlette/concurrency.py", line 38, in run_in_threadpool
    return await anyio.to_thread.run_sync(func)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/anyio/to_thread.py", line 56, in run_sync
    return await get_async_backend().run_sync_in_worker_thread(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/anyio/_backends/_asyncio.py", line 2485, in run_sync_in_worker_thread
    return await future
           ^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/anyio/_backends/_asyncio.py", line 976, in run
    result = context.run(func, *args)
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/routers/update_router.py", line 35, in update_all_directories
    return [service.update(directory, since, ura_whitelist) for directory in directories]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/routers/update_router.py", line 35, in <listcomp>
    return [service.update(directory, since, ura_whitelist) for directory in directories]
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/update/update_client_service.py", line 166, in update
    self.update_resource(directory, res.value, cache_service, since, ura_whitelist)
  File "/src/app/services/update/update_client_service.py", line 228, in update_resource
    nodes = self.update_page(targets, adjacency_map_service)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/update/update_client_service.py", line 243, in update_page
    adj_map = adjacency_map_service.build_adjacency_map(entries)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/update/adjacency_map_service.py", line 67, in build_adjacency_map
    nodes = [self.create_node(entry) for entry in entries]
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/update/adjacency_map_service.py", line 67, in <listcomp>
    nodes = [self.create_node(entry) for entry in entries]
             ^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/update/adjacency_map_service.py", line 208, in create_node
    references = self.create_node_references(entry)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/update/adjacency_map_service.py", line 230, in create_node_references
    reference_node = FhirService.make_reference_node(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/fhir/fhir_service.py", line 70, in make_reference_node
    return build_node_reference(data, base_url)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/app/services/fhir/references/reference_misc.py", line 21, in build_node_reference
    raise ValueError("Invalid absolute URL found")
ValueError: Invalid absolute URL found

4. Return the reference to an relative url like this:

{
  "resourceType": "Organization",
  "id": "default-3",
  "endpoint": [
    {
      "reference": "Endpoint/default-2"
    }
  ]
}

5. When doing update_resource again, we see the same error again

Expected behavior:

• Nicer error handing (application crashes now)
• Error to disappear when restoring the reference url to relative.