Harden crash-prone force-unwraps and traps

Hemera/AppEnvironment.swift

@@ -29,7 +29,13 @@ final class AppEnvironment {
         } catch {
             Log.error("ModelContainer creation failed — deleting store (HomeTile layout will be lost). Error: \(error)")
             Self.deleteStore(at: modelConfig.url)
-            self.container = try! ModelContainer(for: schema, configurations: modelConfig)
+            do {
+                self.container = try ModelContainer(for: schema, configurations: modelConfig)
+            } catch {
+                Log.error("ModelContainer recreation failed after store deletion — falling back to in-memory container (no persistence this session). Error: \(error)")
+                let memoryConfig = ModelConfiguration(isStoredInMemoryOnly: true)
+                self.container = try! ModelContainer(for: schema, configurations: memoryConfig)
+            }
         }
 
         self.storage = SwiftDataStorage(context: container.mainContext)

Hemera/HomeAssistant/MDISymbolMapper.swift

@@ -1,4 +1,5 @@
 import Foundation
+import HemeraLog
 
 /// Maps Material Design Icon (MDI) names from Home Assistant to SF Symbol names.
 ///
@@ -31,18 +32,24 @@ enum MDISymbolMapper {
 
     private static func loadMapping(from resource: String) -> [String: String] {
         guard let url = Bundle.main.url(forResource: resource, withExtension: "json") else {
-            preconditionFailure("\(resource).json missing from bundle")
+            Log.error("\(resource).json missing from bundle — icon mapping disabled for \(resource)")
+            return [:]
         }
-        let data = try! Data(contentsOf: url)
-        let entries = try! JSONDecoder().decode([Entry].self, from: data)
-
-        var map: [String: String] = [:]
-        for entry in entries {
-            for mdiName in entry.mdiNames {
-                map[mdiName] = entry.sfSymbol
+        do {
+            let data = try Data(contentsOf: url)
+            let entries = try JSONDecoder().decode([Entry].self, from: data)
+
+            var map: [String: String] = [:]
+            for entry in entries {
+                for mdiName in entry.mdiNames {
+                    map[mdiName] = entry.sfSymbol
+                }
             }
+            return map
+        } catch {
+            Log.error("Failed to load \(resource).json — icon mapping disabled", cause: error)
+            return [:]
         }
-        return map
     }
 }
 

Hemera/SessionManager.swift

@@ -88,7 +88,10 @@ final class SessionManager: ConnectionRetrying {
         Log.info("Starting demo session")
 
         let demoConfig = ModelConfiguration(isStoredInMemoryOnly: true)
-        let demoContainer = try! ModelContainer(for: AppEnvironment.createSchema(), configurations: demoConfig)
+        guard let demoContainer = try? ModelContainer(for: AppEnvironment.createSchema(), configurations: demoConfig) else {
+            Log.error("Failed to create in-memory demo container — aborting demo session")
+            return
+        }
         self.demoContainer = demoContainer
         let demoContext = demoContainer.mainContext
 

Hemera/UI/RootView.swift

@@ -24,9 +24,18 @@ struct RootView: View {
             case .connecting:
                 ConnectingView(viewModel: ConnectingViewModel())
             case .authenticated:
-                MainTabView(viewModel: MainTabViewModel())
-                    .modelContainer(ServiceLocator.shared.session!.container)
-                    .transaction { $0.animation = nil }
+                if let session = ServiceLocator.shared.session {
+                    MainTabView(viewModel: MainTabViewModel())
+                        .modelContainer(session.container)
+                        .transaction { $0.animation = nil }
+                } else {
+                    /**
+                     Session torn down while destination is briefly still .authenticated.
+                     Render nothing rather than crashing; the router handler will move
+                     destination away from .authenticated on the same runloop turn.
+                     */
+                    Color.clear
+                }
             }
         }
         .environment(authManager)

Hemera/UI/Settings/AuthenticatedWebView.swift

@@ -43,11 +43,16 @@ struct AuthenticatedWebView: UIViewRepresentable {
         let webView = WKWebView(frame: .zero, configuration: config)
         context.coordinator.webView = webView
 
-        var components = URLComponents(url: url, resolvingAgainstBaseURL: false)!
-        components.queryItems = (components.queryItems ?? []) + [
-            URLQueryItem(name: "external_auth", value: "1")
-        ]
-        webView.load(URLRequest(url: components.url!))
+        let requestURL: URL
+        if var components = URLComponents(url: url, resolvingAgainstBaseURL: false) {
+            components.queryItems = (components.queryItems ?? []) + [
+                URLQueryItem(name: "external_auth", value: "1")
+            ]
+            requestURL = components.url ?? url
+        } else {
+            requestURL = url
+        }
+        webView.load(URLRequest(url: requestURL))
         return webView
     }
 

HemeraTests/HomeAssistant/MDISymbolMapperTests.swift

@@ -144,6 +144,14 @@ struct MDISymbolMapperTests {
         }
     }
 
+    @Test func bundledMaps_decodeToNonEmpty() throws {
+        for file in ["AreaMdiToSymbolMap", "EntityMdiToSymbolMap"] {
+            let entries = try loadEntries(from: file)
+            #expect(!entries.isEmpty)
+            #expect(entries.allSatisfy { !$0.mdiNames.isEmpty })
+        }
+    }
+
     // MARK: - Helpers
 
     private struct MappingEntry: Decodable {

HemeraTests/Navigation/SessionManagerDemoTests.swift

@@ -63,6 +63,19 @@ struct SessionManagerTests {
         #expect(ServiceLocator.shared.session != nil)
     }
 
+    @Test
+    func inMemoryDemoContainer_withCurrentSchema_buildsAndIsQueryable() throws {
+        /**
+         Guards the graceful demo-container fallback in `startDemoSession`: if the
+         current schema ever stopped building an in-memory container, the demo path
+         would silently no-op. This fails loudly instead.
+         */
+        let config = ModelConfiguration(isStoredInMemoryOnly: true)
+        let container = try ModelContainer(for: AppEnvironment.createSchema(), configurations: config)
+        let count = try container.mainContext.fetchCount(FetchDescriptor<AreaEntity>())
+        #expect(count == 0)
+    }
+
     // MARK: - tearDownDemoSession
 
     @Test