Fix unincluded umbrella warnings (#5226)

FirebaseCore/CHANGELOG.md

@@ -1,3 +1,7 @@
+# v6.6.6 -- M68
+- [fixed] Unincluded umbrella header warnings in Carthage and zip distributions
+  introduced in Firebase 6.21.0. (#5209)
+
 # v6.6.5 -- M67
 - [changed] The zip distribution is now comprised of xcframeworks instead of
   frameworks. This provides a binary distribution for the community supported

ZipBuilder/Sources/ZipBuilder/FrameworkBuilder.swift

@@ -468,11 +468,10 @@ struct FrameworkBuilder {
         if umbrellas.count != 1 {
           fatalError("Did not find exactly one umbrella header in \(headersDir).")
         }
-        guard let firstUmbrella = umbrellas.first,
-          let foundHeader = URL(string: firstUmbrella) else {
+        guard let firstUmbrella = umbrellas.first else {
           fatalError("Failed to get umbrella header in \(headersDir).")
         }
-        umbrellaHeaderURL = foundHeader
+        umbrellaHeaderURL = URL(fileURLWithPath: firstUmbrella)
       } catch {
         fatalError("Error while enumerating files \(headersDir): \(error.localizedDescription)")
       }
@@ -485,7 +484,7 @@ struct FrameworkBuilder {
         do {
           try fileManager.removeItem(at: umbrellaHeaderURL)
         } catch let error as NSError {
-          print("Failed to delete: \(umbrellaHeaderURL). Error: \(error.domain)")
+          fatalError("Failed to delete: \(umbrellaHeaderURL). Error: \(error.domain)")
         }
         umbrellaHeader = "\(framework).h"
         let frameworkHeader = headersDir.appendingPathComponent(umbrellaHeader)