Ktor 0.9.1-alpha9 issue

gistfile1.txt

Exception in thread "nettyCallPool-4-1" java.lang.UnsupportedOperationException: Headers can no longer be set because response was already completed
	at io.ktor.server.netty.http1.NettyHttp1ApplicationResponse$headers$1.engineAppendHeader(NettyHttp1ApplicationResponse.kt:34)
	at io.ktor.response.ResponseHeaders.append(ResponseHeaders.kt:19)
	at io.ktor.response.ResponseHeaders.append$default(ResponseHeaders.kt:16)
	at io.ktor.response.ResponseCookies.append(ResponseCookies.kt:13)
	at io.ktor.sessions.SessionTransportCookie.send(SessionTransportCookie.kt:33)
	at io.ktor.sessions.Sessions$Feature$install$2.doResume(Sessions.kt:52)
	at io.ktor.sessions.Sessions$Feature$install$2.invoke(Sessions.kt)
	at io.ktor.sessions.Sessions$Feature$install$2.invoke(Sessions.kt:18)
	at io.ktor.pipeline.PipelineContext.proceed(PipelineContext.kt:49)
	at io.ktor.pipeline.Pipeline.execute(Pipeline.kt:22)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$2.doResume(DefaultEnginePipeline.kt:76)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:60)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:59)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:59)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:59)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:59)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:59)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:59)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlinx.coroutines.experimental.DispatchedTask$DefaultImpls.run(Dispatched.kt:161)
	at kotlinx.coroutines.experimental.AbstractContinuation.run(AbstractContinuation.kt:31)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:462)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
	at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
	at java.lang.Thread.run(Thread.java:748)
2018-01-17 12:32:24.503 [nettyCallPool-4-1] ERROR ktor.application - 200 OK: GET - /
java.lang.UnsupportedOperationException: Headers can no longer be set because response was already completed
	at io.ktor.server.netty.http1.NettyHttp1ApplicationResponse$headers$1.engineAppendHeader(NettyHttp1ApplicationResponse.kt:34)
	at io.ktor.response.ResponseHeaders.append(ResponseHeaders.kt:19)
	at io.ktor.response.ResponseHeaders.append$default(ResponseHeaders.kt:16)
	at io.ktor.response.ResponseCookies.append(ResponseCookies.kt:13)
	at io.ktor.sessions.SessionTransportCookie.send(SessionTransportCookie.kt:33)
	at io.ktor.sessions.Sessions$Feature$install$2.doResume(Sessions.kt:52)
	at io.ktor.sessions.Sessions$Feature$install$2.invoke(Sessions.kt)
	at io.ktor.sessions.Sessions$Feature$install$2.invoke(Sessions.kt:18)
	at io.ktor.pipeline.PipelineContext.proceed(PipelineContext.kt:49)
	at io.ktor.pipeline.Pipeline.execute(Pipeline.kt:22)
	at io.ktor.content.StaticContentKt$defaultResource$1.doResume(StaticContent.kt:152)
	at io.ktor.content.StaticContentKt$defaultResource$1.invoke(StaticContent.kt)
	at io.ktor.content.StaticContentKt$defaultResource$1.invoke(StaticContent.kt)
	at io.ktor.pipeline.PipelineContext.proceed(PipelineContext.kt:49)
	at io.ktor.pipeline.PipelineContext$proceed$1.doResume(PipelineContext.kt)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:54)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlinx.coroutines.experimental.DispatchedTask$DefaultImpls.run(Dispatched.kt:161)
	at kotlinx.coroutines.experimental.AbstractContinuation.run(AbstractContinuation.kt:31)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:462)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
	at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
	at java.lang.Thread.run(Thread.java:748)