NullPointerException when expression=encryption:create-expression uses resolver with invalid secret-key

[standalone@localhost:9990 /] /subsystem=elytron/secret-key-credential-store=credentialstorethree:read-aliases
{
    "outcome" => "success",
    "result" => [
        "secretkey",
        "key"
    ]
}

[standalone@localhost:9990 /] /subsystem=elytron/expression=encryption:read-resource
{
    "outcome" => "success",
    "result" => {
        "default-resolver" => "Default",
        "prefix" => "ENC",
        "resolvers" => [
            {
                "name" => "Default",
                "credential-store" => "credentialstorethree",
                "secret-key" => "secretkey"
            },
            {
                "name" => "resolver2",
                "credential-store" => "credentialstorethree",
                "secret-key" => "secretkey2"
            }
        ]
    }
}

[standalone@localhost:9990 /] /subsystem=elytron/expression=encryption:create-expression(clear-text=CredentialStoreTwoPassword)
{
    "outcome" => "success",
    "result" => {"expression" => "${ENC::RUxZAUMQ+LZYf7LtJiSPV4EqY4FEk3WK2V2i4ywGhTTu/3uRQirYtvphB2A8fmK6CSlUnYUd}"}
}

[standalone@localhost:9990 /] /subsystem=elytron/expression=encryption:create-expression(clear-text=CredentialStoreTwoPassword,resolver=resolver2)
{
    "outcome" => "failed",
    "failure-description" => "WFLYCTL0158: Operation handler failed: java.lang.NullPointerException",
    "rolled-back" => true
}

08:52:49,669 ERROR [org.jboss.as.controller.management-operation] (management-handler-thread - 1) WFLYCTL0013: Operation ("create-expression") failed - address: ([
    ("subsystem" => "elytron"),
    ("expression" => "encryption")
]): java.lang.NullPointerException
	at org.wildfly.extension.elytron@15.0.0.Beta1-SNAPSHOT//org.wildfly.extension.elytron.expression.ElytronExpressionResolver.createExpression(ElytronExpressionResolver.java:139)
	at org.wildfly.extension.elytron@15.0.0.Beta1-SNAPSHOT//org.wildfly.extension.elytron.ExpressionResolverResourceDefinition$CreateExpressionHandler.executeRuntimeStep(ExpressionResolverResourceDefinition.java:217)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.AbstractRuntimeOnlyHandler$1.execute(AbstractRuntimeOnlyHandler.java:59)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.AbstractOperationContext.executeStep(AbstractOperationContext.java:1040)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.AbstractOperationContext.processStages(AbstractOperationContext.java:779)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.AbstractOperationContext.executeOperation(AbstractOperationContext.java:468)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.OperationContextImpl.executeOperation(OperationContextImpl.java:1415)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.ModelControllerImpl.internalExecute(ModelControllerImpl.java:431)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.ModelControllerImpl.lambda$execute$1(ModelControllerImpl.java:248)
	at org.wildfly.security.elytron-private@1.14.3.CR1-SNAPSHOT//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:304)
	at org.wildfly.security.elytron-private@1.14.3.CR1-SNAPSHOT//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:270)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.ModelControllerImpl.execute(ModelControllerImpl.java:248)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler.doExecute(ModelControllerClientOperationHandler.java:240)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler.access$400(ModelControllerClientOperationHandler.java:138)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1$1.run(ModelControllerClientOperationHandler.java:162)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1$1.run(ModelControllerClientOperationHandler.java:158)
	at org.wildfly.security.elytron-private@1.14.3.CR1-SNAPSHOT//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:328)
	at org.wildfly.security.elytron-private@1.14.3.CR1-SNAPSHOT//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:285)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.AccessAuditContext.doAs(AccessAuditContext.java:254)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.AccessAuditContext.doAs(AccessAuditContext.java:225)
	at org.jboss.as.controller@15.0.0.Beta1-SNAPSHOT//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1.execute(ModelControllerClientOperationHandler.java:158)
	at org.jboss.as.protocol@15.0.0.Beta1-SNAPSHOT//org.jboss.as.protocol.mgmt.ManagementRequestContextImpl$1.doExecute(ManagementRequestContextImpl.java:70)
	at org.jboss.as.protocol@15.0.0.Beta1-SNAPSHOT//org.jboss.as.protocol.mgmt.ManagementRequestContextImpl$AsyncTaskRunner.run(ManagementRequestContextImpl.java:160)
	at org.jboss.threads@2.4.0.Final//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
	at org.jboss.threads@2.4.0.Final//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1990)
	at org.jboss.threads@2.4.0.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
	at org.jboss.threads@2.4.0.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
	at java.base/java.lang.Thread.run(Thread.java:834)
	at org.jboss.threads@2.4.0.Final//org.jboss.threads.JBossThread.run(JBossThread.java:513)