JPA Form Based Authentication throws NullPointerException if username is incorrect

[webfolderio]

Describe the bug
Form based JPA authentication throws NullPointerException if username is incorrect.

Expected behavior
Quarkus should be return HTTP 403.

Actual behavior
Quarkus returns HTTP 500 and throws NullPointerException.

java.lang.NullPointerException
	at io.quarkus.vertx.http.runtime.security.PersistentLoginManager.save(PersistentLoginManager.java:118)
	at io.quarkus.vertx.http.runtime.security.FormAuthenticationMechanism$1$1$1.accept(FormAuthenticationMechanism.java:78)
	at io.quarkus.vertx.http.runtime.security.FormAuthenticationMechanism$1$1$1.accept(FormAuthenticationMechanism.java:74)
	at io.smallrye.mutiny.helpers.UniCallbackSubscriber.onItem(UniCallbackSubscriber.java:68)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.lambda$onItem$1(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.context.SmallRyeThreadContext.lambda$withContext$0(SmallRyeThreadContext.java:217)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.onItem(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.mutiny.operators.UniSerializedSubscriber.onItem(UniSerializedSubscriber.java:72)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.lambda$onItem$1(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.context.SmallRyeThreadContext.lambda$withContext$0(SmallRyeThreadContext.java:217)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.onItem(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.mutiny.operators.UniSerializedSubscriber.onItem(UniSerializedSubscriber.java:72)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.lambda$onItem$1(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.context.SmallRyeThreadContext.lambda$withContext$0(SmallRyeThreadContext.java:217)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.onItem(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.mutiny.operators.UniSerializedSubscriber.onItem(UniSerializedSubscriber.java:72)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.lambda$onItem$1(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.context.SmallRyeThreadContext.lambda$withContext$0(SmallRyeThreadContext.java:217)
	at io.smallrye.mutiny.context.ContextPropagationUniInterceptor$1.onItem(ContextPropagationUniInterceptor.java:35)
	at io.smallrye.mutiny.operators.UniSerializedSubscriber.onItem(UniSerializedSubscriber.java:72)
	at io.smallrye.mutiny.operators.DefaultUniEmitter.complete(DefaultUniEmitter.java:36)
	at io.quarkus.security.runtime.QuarkusIdentityProviderManagerImpl$1$1$1$1.run(QuarkusIdentityProviderManagerImpl.java:58)
	at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
	at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:2046)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1578)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1452)
	at org.jboss.threads.DelegatingRunnable.run(DelegatingRunnable.java:29)
	at org.jboss.threads.ThreadLocalResettingRunnable.run(ThreadLocalResettingRunnable.java:29)
	at java.base/java.lang.Thread.run(Thread.java:832)
	at org.jboss.threads.JBossThread.run(JBossThread.java:479)

To Reproduce
Steps to reproduce the behavior:

1. git clone https://github.com/webfolderio/quarkus-quickstarts
2. cd quarkus-quickstarts/security-jpa-quickstart
3. mvn test

Configuration

quarkus.datasource.url=jdbc:postgresql:elytron_security_jpa
quarkus.datasource.driver=org.postgresql.Driver
quarkus.datasource.username=quarkus
quarkus.datasource.password=quarkus

quarkus.hibernate-orm.database.generation=drop-and-create

quarkus.http.auth.form.enabled=true

quarkus.log.category."io.quarkus".level=INFO
quarkus.log.category."org.hibernate.SQL".level=DEBUG

Environment (please complete the following information):

• Output of uname -a or ver:

Microsoft Windows [Version 10.0.19041.450]

• Output of java -version:

java version "12.0.1" 2019-04-16
Java(TM) SE Runtime Environment (build 12.0.1+12)
Java HotSpot(TM) 64-Bit Server VM (build 12.0.1+12, mixed mode, sharing)

• Quarkus version or git rev:
  1.7.2.Final

• Build tool (ie. output of mvnw --version or gradlew --version):

Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: C:\maven\bin\..
Java version: 12.0.1, vendor: Oracle Corporation, runtime: C:\java\jdk-12.0.1
Default locale: en_US, platform encoding: utf-8
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

Additional context

FormAuthJpaTestCase.java tests only happy path. It will nice to test when username is not exist.

If username is incorrect, generated byte code returns null. It will better to throw exception instead of returning null.
QuarkusSecurityJpaProcessor.java#L172