fix validation error propagation

Sources/AsyncHTTPClient/HTTPHandler.swift

@@ -554,10 +554,10 @@ extension HTTPClient {
 
         func fail<Delegate: HTTPClientResponseDelegate>(with error: Error, delegateType: Delegate.Type) {
             if let connection = self.connection {
-                connection.channel.close(promise: nil)
                 self.releaseAssociatedConnection(delegateType: delegateType, closing: true)
                     .whenSuccess {
                         self.promise.fail(error)
+                        connection.channel.close(promise: nil)
                     }
             }
         }
@@ -729,7 +729,7 @@ extension TaskHandler: ChannelDuplexHandler {
             try headers.validate(method: request.method, body: request.body)
         } catch {
             promise?.fail(error)
-            context.fireErrorCaught(error)
+            self.failTaskAndNotifyDelegate(error: error, self.delegate.didReceiveError)
             self.state = .end
             return
         }

Tests/AsyncHTTPClientTests/HTTPClientTests+XCTest.swift

@@ -96,6 +96,7 @@ extension HTTPClientTests {
             ("testRacePoolIdleConnectionsAndGet", testRacePoolIdleConnectionsAndGet),
             ("testAvoidLeakingTLSHandshakeCompletionPromise", testAvoidLeakingTLSHandshakeCompletionPromise),
             ("testAsyncShutdown", testAsyncShutdown),
+            ("testValidationErrorsAreSurfaced", testValidationErrorsAreSurfaced),
         ]
     }
 }

Tests/AsyncHTTPClientTests/HTTPClientTests.swift

@@ -1667,7 +1667,7 @@ class HTTPClientTests: XCTestCase {
         }
     }
 
-    func testAsyncShutdown() {
+    func testAsyncShutdown() throws {
         let httpClient = HTTPClient(eventLoopGroupProvider: .shared(self.clientGroup))
         let promise = self.clientGroup.next().makePromise(of: Void.self)
         self.clientGroup.next().execute {
@@ -1678,4 +1678,21 @@ class HTTPClientTests: XCTestCase {
         }
         XCTAssertNoThrow(try promise.futureResult.wait())
     }
+
+    func testValidationErrorsAreSurfaced() throws {
+        let httpBin = HTTPBin()
+        let httpClient = HTTPClient(eventLoopGroupProvider: .shared(self.clientGroup))
+        defer {
+            XCTAssertNoThrow(try httpClient.syncShutdown())
+            XCTAssertNoThrow(try httpBin.shutdown())
+        }
+
+        let request = try HTTPClient.Request(url: "http://localhost:\(httpBin.port)/get", method: .TRACE, body: .stream { _ in
+            httpClient.eventLoopGroup.next().makeSucceededFuture(())
+        })
+        let runningRequest = httpClient.execute(request: request)
+        XCTAssertThrowsError(try runningRequest.wait()) { error in
+            XCTAssertEqual(HTTPClientError.traceRequestWithBody, error as? HTTPClientError)
+        }
+    }
 }