Use constant (IOS-192)

Mastodon/Scene/MediaPreview/MediaPreviewViewModel.swift

@@ -11,6 +11,7 @@ import CoreData
 import CoreDataStack
 import Pageboy
 import MastodonCore
+import MastodonSDK
 
 protocol MediaPreviewPage: UIViewController {
     func setShowingChrome(_ showingChrome: Bool)
@@ -152,7 +153,7 @@ extension MediaPreviewViewModel {
             case .profileBanner(let item):
                 guard let assertURL = item.assetURL else { return false }
 
-                return assertURL.hasSuffix("missing.png") == false
+                return assertURL.hasSuffix(Mastodon.Entity.Account.missingImageName) == false
             }
         }
     }

Mastodon/Scene/Profile/Header/ProfileHeaderViewController.swift

@@ -105,7 +105,6 @@ final class ProfileHeaderViewController: UIViewController, NeedsDependency, Medi
     override func viewDidLoad() {
         super.viewDidLoad()
 
-
         view.setContentHuggingPriority(.required - 1, for: .vertical)
 
         view.backgroundColor = .systemBackground

MastodonSDK/Sources/MastodonSDK/Entity/Mastodon+Entity+Account.swift

@@ -144,7 +144,7 @@ extension Mastodon.Entity.Account {
     }
 
     public func avatarImageURLWithFallback(domain: String) -> URL {
-        return avatarImageURL() ?? URL(string: "https://\(domain)/avatars/original/missing.png")!
+        return avatarImageURL() ?? URL(string: "https://\(domain)/avatars/original/\(Self.missingImageName)")!
     }
 
     public var displayNameWithFallback: String {
@@ -163,3 +163,7 @@ extension Mastodon.Entity.Account {
     }
 
 }
+
+extension Mastodon.Entity.Account {
+    public static let missingImageName = "missing.png"
+}