Fix crashes from forced casts on explicit-null Nightscout fields; copied from PR #794

LoopFollow/Controllers/Nightscout/DeviceStatus.swift

@@ -92,7 +92,7 @@ extension MainViewController {
 
         Observable.shared.previousAlertLastLoopTime.value = Observable.shared.alertLastLoopTime.value
 
-        if let lastPumpRecord = lastDeviceStatus?["pump"] as! [String: AnyObject]? {
+        if let lastPumpRecord = lastDeviceStatus?["pump"] as? [String: AnyObject] {
             if let bolusIncrement = lastPumpRecord["bolusIncrement"] as? Double, bolusIncrement > 0 {
                 Storage.shared.bolusIncrement.value = HKQuantity(unit: .internationalUnit(), doubleValue: bolusIncrement)
                 Storage.shared.bolusIncrementDetected.value = true
@@ -182,10 +182,10 @@ extension MainViewController {
         }
 
         // Loop - handle new data
-        if let lastLoopRecord = lastDeviceStatus?["loop"] as! [String: AnyObject]? {
+        if let lastLoopRecord = lastDeviceStatus?["loop"] as? [String: AnyObject] {
             // Some pumps report no `pump.clock`; without it alertLastLoopTime stays 0
             // and the forecast anchors to epoch 0. Fall back to the loop cycle timestamp.
-            if (lastDeviceStatus?["pump"] as? [String: AnyObject])?["clock"] == nil,
+            if (lastDeviceStatus?["pump"] as? [String: AnyObject])?["clock"] as? String == nil,
                let loopTimestampString = lastLoopRecord["timestamp"] as? String,
                let loopTimestamp = formatter.date(from: loopTimestampString)?.timeIntervalSince1970,
                loopTimestamp > (Observable.shared.alertLastLoopTime.value ?? 0)
@@ -223,7 +223,7 @@ extension MainViewController {
         }
 
         // OpenAPS - handle new data
-        if let lastLoopRecord = lastDeviceStatus?["openaps"] as! [String: AnyObject]? {
+        if let lastLoopRecord = lastDeviceStatus?["openaps"] as? [String: AnyObject] {
             DeviceStatusOpenAPS(formatter: formatter, lastDeviceStatus: lastDeviceStatus, lastLoopRecord: lastLoopRecord)
         }
 

LoopFollow/Controllers/Nightscout/DeviceStatusLoop.swift

@@ -32,7 +32,7 @@ extension MainViewController {
         Storage.shared.lastIOB.value = latestIOB?.value
         Storage.shared.lastCOB.value = latestCOB?.value
 
-        if lastLoopRecord["failureReason"] != nil {
+        if let failureReason = lastLoopRecord["failureReason"], !(failureReason is NSNull) {
             Observable.shared.loopStatusText.value = "X"
             latestLoopStatusString = "X"
         } else {

LoopFollow/Controllers/Nightscout/DeviceStatusOpenAPS.swift

@@ -7,7 +7,7 @@ import HealthKit
 extension MainViewController {
     func DeviceStatusOpenAPS(formatter: ISO8601DateFormatter, lastDeviceStatus: [String: AnyObject]?, lastLoopRecord: [String: AnyObject]) {
         Storage.shared.device.value = lastDeviceStatus?["device"] as? String ?? ""
-        if lastLoopRecord["failureReason"] != nil {
+        if let failureReason = lastLoopRecord["failureReason"], !(failureReason is NSNull) {
             Observable.shared.loopStatusText.value = "X"
             latestLoopStatusString = "X"
         } else {

Tests/DeviceStatusHistoryTests.swift

@@ -6,13 +6,13 @@ import Foundation
 import Testing
 
 struct DeviceStatusHistoryParserTests {
-    private func json(_ text: String) -> [String: Any] {
-        try! JSONSerialization.jsonObject(with: Data(text.utf8)) as! [String: Any]
+    private func json(_ text: String) throws -> [String: Any] {
+        try #require(JSONSerialization.jsonObject(with: Data(text.utf8)) as? [String: Any])
     }
 
     @Test("Loop record yields IOB, COB and the forecast from its start date")
     func loopRecord() throws {
-        let record = json("""
+        let record = try json("""
         {"created_at": "2026-09-27T10:00:30.000Z",
          "loop": {"timestamp": "2026-09-27T10:00:05Z",
                   "iob": {"iob": 1.25, "timestamp": "2026-09-27T10:00:00Z"},
@@ -32,7 +32,7 @@ struct DeviceStatusHistoryParserTests {
 
     @Test("Trio record yields smoothed BG, ISF, ratio and the four forecast curves")
     func trioRecord() throws {
-        let record = json("""
+        let record = try json("""
         {"created_at": "2026-09-27T10:00:30.000Z", "device": "Trio",
          "pump": {"reservoir": 120.5, "battery": {"percent": 80}}, "uploader": {"battery": 55},
          "openaps": {"iob": {"iob": 2.5, "time": "2026-09-27T10:00:00Z"},
@@ -61,7 +61,7 @@ struct DeviceStatusHistoryParserTests {
 
     @Test("Loop's active override is kept")
     func loopOverride() throws {
-        let record = json("""
+        let record = try json("""
         {"created_at": "2026-09-27T10:00:30Z",
          "override": {"active": true, "multiplier": 1.5, "currentCorrectionRange": {"minValue": 90, "maxValue": 100}},
          "loop": {"timestamp": "2026-09-27T10:00:05Z", "recommendedBolus": 0.4}}
@@ -73,7 +73,7 @@ struct DeviceStatusHistoryParserTests {
 
     @Test("A zero ISF is a placeholder, COB falls back to the reason string")
     func openAPSFallbacks() throws {
-        let record = json("""
+        let record = try json("""
         {"created_at": "2026-09-27T10:00:30Z",
          "openaps": {"iob": [{"iob": 0.8}, {"iob": 0.6}],
                      "enacted": {"timestamp": "2026-09-27T10:00:00Z", "ISF": 0,
@@ -87,7 +87,7 @@ struct DeviceStatusHistoryParserTests {
 
     @Test("Out-of-range forecast values are clamped")
     func hugeForecastValue() throws {
-        let record = json("""
+        let record = try json("""
         {"created_at": "2026-09-27T10:00:30Z",
          "loop": {"timestamp": "2026-09-27T10:00:05Z", "predicted": {"values": [1e30, -5, 120]}}}
         """)
@@ -96,13 +96,26 @@ struct DeviceStatusHistoryParserTests {
     }
 
     @Test("Uploader-only records carry nothing to graph")
-    func uploaderOnly() {
-        let record = json("""
+    func uploaderOnly() throws {
+        let record = try json("""
         {"created_at": "2026-09-27T10:00:30Z", "uploader": {"battery": 80}}
         """)
         #expect(DeviceStatusHistoryParser.parse(record) == nil)
     }
 
+    @Test("Explicit nulls are treated as missing fields")
+    func explicitNulls() throws {
+        let record = try json("""
+        {"created_at": "2026-09-27T10:00:30Z", "loop": null, "override": null, "pump": {"clock": null},
+         "openaps": {"iob": [{"iob": 0.8}], "suggested": null,
+                     "enacted": {"timestamp": "2026-09-27T10:00:00Z", "COB": 12, "ISF": null}}}
+        """)
+        let (sample, _) = try #require(DeviceStatusHistoryParser.parse(record))
+        #expect(sample.iob == 0.8)
+        #expect(sample.cob == 12)
+        #expect(sample.isf == nil)
+    }
+
     @Test("Offsets are honored")
     func offsetDates() {
         let utc = DeviceStatusHistoryParser.parseDate("2026-09-27T10:00:00Z")