• If The TLD file has missing <uri> tag in it then rather than validating WildFly throws NullPointerException.

WEB-INF/custom.tld

<taglib>
  <tlib-version>1.0</tlib-version>
  <jsp-version>2.0</jsp-version>
  <!--uri>test</uri-->
  <short-name>Example TLD with Body</short-name>
  <tag>
    <name>Hello</name>
    <tag-class&gt;tags.HelloTag</tag-class&gt;
    <body-content>scriptless</body-content>
  </tag>
</taglib>

• During deployment of a war containing above TLD causes following NullPointerException on WildFly:

  13:15:25,857 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-2) MSC000001: Failed to start service jboss.undertow.deployment.default-server.default-host./TagClassDemo.UndertowDeploymentInfoService: org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-server.default-host./TagClassDemo.UndertowDeploymentInfoService: Failed to start service
  	at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1904) [jboss-msc-1.2.2.Final.jar:1.2.2.Final]
  	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_51]
  	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_51]
  	at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_51]
  Caused by: java.lang.NullPointerException
  	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService.createTldsInfo(UndertowDeploymentInfoService.java:1028)
  	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService.createServletConfig(UndertowDeploymentInfoService.java:552)
  	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService.start(UndertowDeploymentInfoService.java:252)
  	at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1948) [jboss-msc-1.2.2.Final.jar:1.2.2.Final]
  	at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1881) [jboss-msc-1.2.2.Final.jar:1.2.2.Final]
  	... 3 more
  
  13:15:25,865 ERROR [org.jboss.as.controller.management-operation] (DeploymentScanner-threads - 1) WFLYCTL0013: Operation ("full-replace-deployment") failed - address: ([]) - failure description: {"WFLYCTL0080: Failed services" => {"jboss.undertow.deployment.default-server.default-host./TagClassDemo.UndertowDeploymentInfoService" => "org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-server.default-host./TagClassDemo.UndertowDeploymentInfoService: Failed to start service
      Caused by: java.lang.NullPointerException"}}