fix(postgrest): allow null reference values in Set

[PhuocOng]

Fixes #171.

Set(row => row.Data, null) rejects reference-type columns other than string before sending a request. The null guard uses Nullable.GetUnderlyingType, which is only applicable to value types. The original report used JObject; the same rejection affects JsonObject in the current System.Text.Json-based SDK, as well as nullable list columns.

Only apply the nullability guard to value types. Reference-type columns can then be cleared, while null for non-nullable value types and non-null values of the wrong type are still rejected. This change is limited to Set(selector, value); the KeyValuePair overload is unchanged.

Five unit cases cover JSON/list references, string and nullable-value controls, and rejection for a non-nullable value type. A request approval test pins {"data":null}. A live PostgREST test exercises Set(...).Update(), checks the target with data=is.null, and verifies a neighboring row keeps its JSON value.

The existing Set tests also gain this. qualification to satisfy the touched-file format gate. No dependency, schema, public-API or cross-SDK parity changes.

Validation

• Before the fix: all four existing Set tests pass; the added null-reference test fails with ArgumentException.
• Full SDK quality gate: bash scripts/quality-gate/gate.sh packages reports PASS, with 935 tests across eight packages, no failures/skips, and live Supabase E2E. The Windows job passes all 153 PostgREST unit/contract tests.

All six files match the verified source. Tests ran on GitHub-hosted runners with a disposable Supabase stack; no production resources or credentials. The fork-only workflow is excluded. No --fast, --bypass-format, --overwrite-baseline, or baseline edits. Public-API diff: no public surface change.

AI-assisted with GitHub Copilot.

Quality gate summary (verbatim)

  [B] Build (analyzers)
        PASS Core        0, at baseline
        PASS Functions   10, at baseline
        PASS Gotrue      278 < baseline 300 — lowering baseline
        PASS Postgrest   134 < baseline 142 — lowering baseline
        PASS Realtime    54, at baseline
        PASS Storage     236, at baseline
        PASS Supabase    16, at baseline
        PASS DependencyInjection 0, at baseline
  [B] Format + naming
        PASS Postgrest   5 changed file(s) clean
  [B] Tests (Unit + Contract + E2E)
        PASS Core        Passed!  - Failed:     0, Passed:    71, Skipped:     0, Total:    71, Duration: 412 ms - Core.Tests.dll (net10.0)
        PASS Functions   Passed!  - Failed:     0, Passed:    53, Skipped:     0, Total:    53, Duration: 1 s - Functions.Tests.dll (net10.0)
        PASS Gotrue      Passed!  - Failed:     0, Passed:   214, Skipped:     0, Total:   214, Duration: 18 s - Gotrue.Tests.dll (net10.0)
        PASS Postgrest   Passed!  - Failed:     0, Passed:   236, Skipped:     0, Total:   236, Duration: 2 s - Postgrest.Tests.dll (net10.0)
        PASS Realtime    Passed!  - Failed:     0, Passed:   132, Skipped:     0, Total:   132, Duration: 13 s - Realtime.Tests.dll (net10.0)
        PASS Storage     Passed!  - Failed:     0, Passed:   171, Skipped:     0, Total:   171, Duration: 3 s - Storage.Tests.dll (net10.0)
        PASS Supabase    Passed!  - Failed:     0, Passed:    54, Skipped:     0, Total:    54, Duration: 443 ms - Supabase.Tests.dll (net10.0)
        PASS DependencyInjection Passed!  - Failed:     0, Passed:     4, Skipped:     0, Total:     4, Duration: 94 ms - DependencyInjection.Tests.dll (net10.0)
  [B] Coverage (line, unit+contract)
        PASS Core        100.00%, at baseline · full incl. E2E: 100.00% (121/121)
        PASS Functions   98.34%, at baseline · full incl. E2E: 98.34% (178/181)
        PASS Gotrue      line coverage 51.20%→53.08% — raising baseline · full incl. E2E: 77.58% (1235/1592)
        PASS Postgrest   70.67%, at baseline · full incl. E2E: 85.40% (1217/1425)
        PASS Realtime    46.50%, at baseline · full incl. E2E: 82.40% (1035/1256)
        PASS Storage     line coverage 77.15%→79.03% — raising baseline · full incl. E2E: 90.59% (972/1073)
        PASS Supabase    82.94%, at baseline · full incl. E2E: 88.49% (223/252)
        PASS DependencyInjection 100.00%, at baseline · full incl. E2E: 100.00% (33/33)
  [s] Dependency vulnerabilities
        PASS none known
  [B] Public API declared
        PASS PublicAPI.*.txt matches the compiled surface
  [s] Public API diff
        PASS no public surface change
GATE: PASS (exit 0) — blocking stages green; signal stages are the maintainer's call.

[fresh55]

LGTM 👍

[PhuocOng]

great, tyty