Avoid closing ServletOutputStream even in case of error

The reason why we shouldn't do is that the stream will be closed
by the container. An attempt to close it after an error could crash
because the underlying stream implementation could be already terminated
and underlying resources could be already recycled.

ktor-server/ktor-server-servlet/src/io/ktor/server/servlet/ServletWriter.kt

@@ -49,7 +49,6 @@ private class ServletWriter(val output: ServletOutputStream) : WriteListener {
             onError(t)
         } finally {
             events.close()
-            output.close()
         }
     }