Fix usages of writeFatalError

Library/Network/ExtensionErrors.swift

@@ -3,3 +3,17 @@ import Foundation
 public enum FullDiskAccessPermissionRequired: Error {
     case error
 }
+
+public class ExtensionStartupError: Error {
+    let message: String
+
+    init(_ message: String) {
+        self.message = message
+    }
+}
+
+extension ExtensionStartupError: LocalizedError {
+    public var errorDescription: String? {
+        message
+    }
+}