Fix: /homekit/accessories returns null when characteristic metadata contains NaN or Infinity (#2)

* Fix JSON encoding crash when HomeKit characteristic values are NaN or Infinity

JSONEncoder throws EncodingError.invalidValue for NaN/Infinity doubles, causing
the accessories endpoint to silently return null via try?. Map these to JSON null
instead so /homekit/accessories encodes correctly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test: cover non-finite HomeKit numbers

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

Casa/HomeKitServer.swift

@@ -793,7 +793,12 @@ enum JSONValue: Encodable {
     func encodedData() -> Data {
         let encoder = JSONEncoder()
         encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
-        return (try? encoder.encode(self)) ?? Data("null".utf8)
+        do {
+            return try encoder.encode(self)
+        } catch {
+            print("[Casa] JSON encoding failed: \(error)")
+            return Data("null".utf8)
+        }
     }
 }
 
@@ -954,7 +959,9 @@ enum HomeKitPayload {
             if CFGetTypeID(number) == CFBooleanGetTypeID() {
                 return .bool(number.boolValue)
             }
-            return .number(number.doubleValue)
+            let d = number.doubleValue
+            if d.isNaN || d.isInfinite { return .null }
+            return .number(d)
         case let string as String:
             return .string(string)
         case let date as Date:

CasaTests/CasaTests.swift

@@ -106,6 +106,49 @@ final class CasaTests: XCTestCase {
         XCTAssertEqual(entry?["maxValue"] as? Double, 100)
     }
 
+    func testSchemaMapsNonFiniteNumbersToNull() throws {
+        let metadata = CasaCharacteristicMetadata(
+            format: HMCharacteristicMetadataFormatFloat,
+            minValue: Double.nan,
+            maxValue: Double.infinity,
+            stepValue: -Double.infinity,
+            validValues: [Double.nan, 1],
+            units: ""
+        )
+        let characteristic = CasaCharacteristic(
+            id: "char-3",
+            type: "type-3",
+            properties: ["read"],
+            metadata: metadata,
+            value: Double.nan
+        )
+        let service = CasaService(
+            id: "svc-3",
+            name: "Service",
+            type: "type",
+            accessoryId: "acc-3",
+            characteristics: [characteristic]
+        )
+        let accessory = CasaAccessory(
+            id: "acc-3",
+            name: "Accessory",
+            category: "Category",
+            room: "Room",
+            hasCameraProfile: false,
+            services: [service]
+        )
+
+        let data = HomeKitPayload.schema([accessory]).encodedData()
+        let json = try JSONSerialization.jsonObject(with: data) as? [[String: Any]]
+        let entry = json?.first
+        XCTAssertTrue(entry?["minValue"] is NSNull)
+        XCTAssertTrue(entry?["maxValue"] is NSNull)
+        XCTAssertTrue(entry?["stepValue"] is NSNull)
+        let validValues = entry?["validValues"] as? [Any]
+        XCTAssertTrue(validValues?.first is NSNull)
+        XCTAssertEqual(validValues?.last as? Double, 1)
+    }
+
     func testSettingsDefaultsAreOff() throws {
         let suiteName = "casa.tests.defaults.\(UUID().uuidString)"
         let defaults = UserDefaults(suiteName: suiteName)!