Error on startup: devcontainersPort cannot be null

[MaxWenzel]

I try it on console and also via IntelliJ Configuration: If I try to start my application with just run command I see the following exception:

2023-03-28T18:19:10.505+02:00 ERROR 28537 --- [  restartedMain] o.s.boot.SpringApplication: Application run failed

 java.lang.IllegalArgumentException: devcontainersPort cannot be null
        at org.springframework.util.Assert.notNull(Assert.java:204)
        at com.maciejwalkowiak.just.spring.boot.DevcontainersClient.<init>(DevcontainersClient.java:22)
        at com.maciejwalkowiak.just.spring.boot.DevcontainersClient.<init>(DevcontainersClient.java:29)
        at com.maciejwalkowiak.just.spring.boot.DevcontainersContextInitializer.initialize(DevcontainersContextInitializer.java:13)
        at org.springframework.boot.SpringApplication.applyInitializers(SpringApplication.java:603)
        at org.springframework.boot.SpringApplication.prepareContext(SpringApplication.java:383)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:307)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1302)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1291)

Do I need the testcontainer dependency to use the tool? I added it (and also the devtools dependency) now but the result is the same.