Wait for completion of chunked body

Package.swift

@@ -11,7 +11,7 @@ let package = Package(
         .package(url: "https://github.com/vapor/vapor.git", from: "3.0.0"),
 
         // 🤐 Unzip archives
-        .package(url: "https://github.com/microtherion/ZIPFoundation.git", .upToNextMajor(from: "0.9.8-µ"))
+        .package(url: "https://github.com/microtherion/ZIPFoundation.git", from: "0.9.9-µ5")
     ],
     targets: [
         .target(name: "GzipMiddleware", dependencies: ["Vapor", "ZIPFoundation"]),

Sources/GzipMiddleware/GzipMiddleware.swift

@@ -51,14 +51,18 @@ public struct GzipServerMiddleware: Middleware, ServiceType {
                             return stream.write(.chunk(buffer))
                         }
                     })
-                write.always {
+                write = write.flatMap {
                     buffer.clear()
                     buffer.write(integer: crc32, endianness: .little)
                     buffer.write(integer: UInt32(data.count), endianness: .little)
-                    stream.write(.chunk(buffer)).always {
+                    return stream.write(.chunk(buffer))
-                        _ = stream.write(.end)
+                }.flatMap {
+                    return stream.write(.end)
                 }
+                DispatchQueue.global().async {
+                    _ = try? write.wait()
                 }
+
                 let httpResponse = HTTPResponse(status: response.http.status, headers: headers, body: stream)
                 return request.response(http: httpResponse)
             }