[Missing text '/headings/heading[@name='Information']/description' for 'English'

I am getting error [Missing text '/headings/heading[@name='Information']/description' for 'English'. I have code like below and when I try to enter data for Student, I get above error message, I can successfully save the data though.

[PropertyDefinitionTypePlugIn]
public class StudentProperty : PropertyListBase<TestimonialList>
{
}
public class Student
{
}

public class StudentBlock : BlockData
{
[EditorDescriptor(EditorDescriptorType = typeof(CollectionEditorDescriptor<Student>))]
public virtual IList<Student> Students{ get; set; }
}