Return 404 instead of 500 for unknown resource type for Sql

[mikaelweave]

Description

SqlServerFhirModel.GetResourceTypeId() performed a case-sensitive dictionary lookup and let
KeyNotFoundException bubble up, producing 500 Internal Server Error for any unknown or
mis-cased resource type that reached the SQL data layer (for example, a case-mismatched
DELETE /patient/{id} that slipped past routing).

Per FHIR, an unknown resource type should produce 404 Not Found, not 500.

Reproduction

1. Start the server.
2. Issue DELETE https://localhost:44348/patient/123?hardDelete=true (lowercase).
3. Current behavior: 500.
4. Expected behavior: 404.

Note: a complementary fix in a separate PR makes the routing layer return 404 for
mis-cased resource type segments before they reach the SQL layer. This PR is the
defense-in-depth fix at the data layer for any path that still reaches it
(e.g. internal callers, future code paths).

Fix

Changed GetResourceTypeId() to use TryGetValue() and throw ResourceNotFoundException
(already mapped to 404 by the exception filter) instead of letting KeyNotFoundException
surface as 500.

Dictionary comparers for resource type lookups remain StringComparer.Ordinal — the FHIR
spec requires case-sensitive resource type matching.

Now this request will return the below as 404 vs a 500

{
  "resourceType": "OperationOutcome",
  "id": "f84d47cb-357b-43f8-9efb-941fd7f512f8",
  "meta": {
    "lastUpdated": "2026-04-29T21:07:03.188648+00:00"
  },
  "issue": [
    {
      "severity": "error",
      "code": "not-found",
      "diagnostics": "Resource type 'patient' is not a known resource type."
    }
  ]
}

Impact

• Fixes incorrect 500 responses for unknown / case-mismatched resource types reaching
  the SQL data layer.
• All other callers of GetResourceTypeId() now get a clean 404 instead of an unhandled 500.
• CosmosDB path is not affected by this bug.

Related Work Items

AB#190027

Testing

• Existing PR coverage for the SQL GetResourceTypeId() path.

Risks and Follow-ups

• Routing-layer fix for mis-cased resource type segments is shipped in a separate PR.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@5bb9494). Learn more about missing BASE report.

Additional details and impacted files

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