Mitigate fatalError() in properties, fail gracefully

Do not trigger fatalError() on properties too much because
SwiftUI may read them at any unpredictable time.

Passepartout/App/Views/ProfileView+Provider.swift

@@ -81,7 +81,7 @@ extension ProfileView {
                     Text(L10n.Profile.Items.Provider.Refresh.caption)
                 }.withTrailingProgress(when: isRefreshingInfrastructure)
             } header: {
-                Text(currentProvider.fullName)
+                currentProviderFullName.map(Text.init)
             } footer: {
                 lastInfrastructureUpdate.map {
                     Text(L10n.Profile.Sections.ProviderInfrastructure.footer($0))
@@ -89,14 +89,16 @@ extension ProfileView {
             }
         }
 
-        private var currentProvider: ProviderMetadata {
+        private var currentProviderFullName: String? {
             guard let name = currentProfile.value.header.providerName else {
-                fatalError("Provider name accessed but profile is not a provider (isPlaceholder? \(currentProfile.value.isPlaceholder))")
+                assertionFailure("Provider name accessed but profile is not a provider (isPlaceholder? \(currentProfile.value.isPlaceholder))")
+                return nil
             }
             guard let metadata = providerManager.provider(withName: name) else {
-                fatalError("Provider metadata not found")
+                assertionFailure("Provider metadata not found")
+                return nil
             }
-            return metadata
+            return metadata.name
         }
 
 //        private var currentProviderLocation: String? {

PassepartoutLibrary/Sources/PassepartoutCore/Extensions/Host+Extensions.swift

@@ -49,30 +49,18 @@ extension Profile {
 
     public var hostOpenVPNSettings: OpenVPNSettings? {
         get {
-            guard host != nil else {
-                fatalError("Not a host")
-            }
             return host?.ovpnSettings
         }
         set {
-            guard host != nil else {
-                fatalError("Not a host")
-            }
             host?.ovpnSettings = newValue
         }
     }
 
     public var hostWireGuardSettings: WireGuardSettings? {
         get {
-            guard host != nil else {
-                fatalError("Not a host")
-            }
             return host?.wgSettings
         }
         set {
-            guard host != nil else {
-                fatalError("Not a host")
-            }
             host?.wgSettings = newValue
         }
     }
@@ -95,7 +83,8 @@ extension Profile.Host: ProfileSubtype {
         } else if let _ = wgSettings {
             return [.wireGuard]
         } else {
-            fatalError("No VPN settings found")
+            assertionFailure("No VPN settings found")
+            return []
         }
     }
 }

PassepartoutLibrary/Sources/PassepartoutVPN/Managers/DefaultVPNManager+Configuration.swift

@@ -75,7 +75,7 @@ extension DefaultVPNManager {
                     settings = try profile.providerOpenVPNSettings(withManager: providerManager)
                 } else {
                     guard let hostSettings = profile.hostOpenVPNSettings else {
-                        fatalError("Host has no OpenVPN settings")
+                        fatalError("Profile currentVPNProtocol is OpenVPN, but host has no OpenVPN settings")
                     }
                     settings = hostSettings
                 }
@@ -87,7 +87,7 @@ extension DefaultVPNManager {
                     settings = try profile.providerWireGuardSettings(withManager: providerManager)
                 } else {
                     guard let hostSettings = profile.hostWireGuardSettings else {
-                        fatalError("Host has no WireGuard settings")
+                        fatalError("Profile currentVPNProtocol is WireGuard, but host has no WireGuard settings")
                     }
                     settings = hostSettings
                 }