Scala Mock NullPointerException (I'm trying to test my scala code using mocking(scalamock) but getting NullPointerException)

Question

I'm new to scalamock I had never use it before , I want to test my scala code using mocking but stuck due to error , here is the full detail.

This project basically get and insert the Student data into scyllaDB , for testing I Don't want to hit the actual database so that's why I'm trying to use scalamock

My build.sbt dependency

libraryDependencies ++=  "org.scalamock" %% "scalamock" % "5.1.0" % "test"

StudentRepository Class for which i want to write a test.

class StudentRepository @Inject()(studentDB: StudentDB) extends StudentRepositoryTrait {

  import studentDB.{session, space}

  override def getStudents: Future[List[StudentData]] = {
    studentDB.Student.select.all().fetch
  }

  override def insertStudentData(student: StudentData): Future[ResultSet] = {
    studentDB.Student
      .store(student)
      .future()
  }
}

here is my StudentDB Class.

class StudentDB(override val connector: CassandraConnection)
  extends Database[StudentDB](connector) {
    object Student extends StudenSchema with Connector
}

Here is my TestClass

class RepositoryMockTesting extends AnyFlatSpec with Matchers with MockFactory {


  val mockStudentDB: StudentDB = mock[StudentDB]
  val studentRepository = new StudentRepository(mockStudentDB)

  val studentData: StudentData = StudentData(Some("Zaman Khan"), Some("1"), Some(""), Some(""), None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None)

  "StudentRepository" should "get students" in {
    val getStudentsResult: Future[List[StudentData]] = studentRepository.getStudents

    getStudentsResult.map { studentList =>
      studentList should not be empty
    }
  }

  it should "insert student data" in {
    val insertStudentsResult: Future[ResultSet] = studentRepository.insertStudentData(studentData)

    insertStudentsResult.map { resultSet =>
      resultSet.wasApplied() should be(true)
    }
  }
}

But I'm getting an error

An exception or error caused a run to abort. 
java.lang.NullPointerException
    at com.outworkers.phantom.database.Database.<init>(Database.scala:35)
    at database.studentdb.StudentDB.<init>(StudentData.scala:7)
    at mocktest.RepositoryMockTesting$$anon$1.<init>(RepositoryMockTesting.scala:53)
    at mocktest.RepositoryMockTesting.<init>(RepositoryMockTesting.scala:53)

Can any one guide me to resolve this error, Any help is appreciated.