rewrite without map

Author: tayloraswift

Package.swift

@@ -5,19 +5,22 @@ import Foundation
 
 /// If we are in a controlled CI environment, we can use internal compiler flags
 /// to speed up the build or improve it.
-let swiftSettings:[SwiftSetting] = ProcessInfo.processInfo.environment["SWIFT_BUILD_SCRIPT_ENVIRONMENT"].map { _ in 
+let swiftSyntaxSwiftSettings:[SwiftSetting] 
+if case _? = ProcessInfo.processInfo.environment["SWIFT_BUILD_SCRIPT_ENVIRONMENT"] {
   let groupFile = URL(fileURLWithPath: #file)
     .deletingLastPathComponent()
     .appendingPathComponent("utils")
     .appendingPathComponent("group.json")
-  return  [.unsafeFlags([
+  swiftSyntaxSwiftSettings = [.unsafeFlags([
     "-Xfrontend", "-group-info-path", 
     "-Xfrontend", groupFile.path, 
     // Enforcing exclusivity increases compile time of release builds by 2 minutes.
     // Disable it when we're in a controlled CI environment.
     "-enforce-exclusivity=unchecked",
   ])]
-} ?? []
+} else {
+    swiftSyntaxSwiftSettings = []
+}
 
 let package = Package(
   name: "SwiftSyntax",
@@ -53,7 +56,7 @@ let package = Package(
         "SyntaxNodes.swift.gyb.template",
         "SyntaxKind.swift.gyb",
       ],
-      swiftSettings: swiftSettings
+      swiftSettings: swiftSyntaxSwiftSettings
     ),
     .target(
       name: "SwiftSyntaxBuilder",