read receipt: do not forcibly unwrap an optional when app groups are not well configured

Author: abarisain

Sources/Swift/Display Receipt/DisplayReceiptCacheHelper.swift

@@ -28,10 +28,11 @@ internal struct DisplayReceiptCacheHelper {
 
     static func sharedDirectory() throws -> URL {
         do {
-            let sharedDir = FileManager
-                .default
-                .containerURL(forSecurityApplicationGroupIdentifier: try self.sharedGroupId())!
-                .appendingPathComponent(Consts.receiptCacheDirectory)
+            guard let sharedDir = FileManager
+                    .default
+                    .containerURL(forSecurityApplicationGroupIdentifier: try self.sharedGroupId())?
+                    .appendingPathComponent(Consts.receiptCacheDirectory)
+            else { throw DisplayReceiptHelperError.appGroupError }
 
             try FileManager.default.createDirectory(at: sharedDir, withIntermediateDirectories: true, attributes: nil)
             return sharedDir

Sources/Swift/Display Receipt/DisplayReceiptHelper.swift

@@ -90,7 +90,7 @@ public enum DisplayReceiptHelperError: Error, CustomNSError {
         case .unpackError:
             return "Error when unpacking receipt"
         case .appGroupError:
-                return "Could not get app group folder"
+            return "Could not get app group folder"
         case .unknownError:
             return "An unknown error occurred"
         }