NullPointerException can happen on the range request in EAP 7

Issue

The following NullPointerException can happen on the request having Range request header in EAP 7:

ERROR [io.undertow.request] (default task-1) UT005071: Undertow request failed HttpServerExchange{ GET /test.txt}: java.lang.NullPointerException
    at io.undertow.server.handlers.resource.PathResource$1ServerTask.run(PathResource.java:156)
    at io.undertow.server.handlers.resource.PathResource$1ServerTask.onComplete(PathResource.java:200)
    at io.undertow.io.AsyncSenderImpl.invokeOnComplete(AsyncSenderImpl.java:413)
    at io.undertow.io.AsyncSenderImpl.send(AsyncSenderImpl.java:173)
    at io.undertow.server.handlers.resource.PathResource$1ServerTask.run(PathResource.java:187)
    at io.undertow.server.handlers.resource.PathResource.serveImpl(PathResource.java:256)
    at io.undertow.server.handlers.resource.PathResource.serveRange(PathResource.java:118)
    at io.undertow.server.handlers.resource.ResourceHandler$1.handleRequest(ResourceHandler.java:335)
    at io.undertow.server.Connectors.executeRootHandler(Connectors.java:376)
    at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830)
    at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1985)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1487)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1349)
    at java.lang.Thread.run(Thread.java:748)