Identifying Situational Irony in Literature

In the novel "The Unexpected Journey," the protagonist, Clara, embarks on an adventure with her overly cautious brother, Henry. They find themselves in a forest where Clara insists on taking a path that she believes will lead them to a hidden treasure, despite Henry's warnings about the dangers ahead.

As they walk deeper into the woods, Clara's confidence begins to wane when they encounter obstacles she had not anticipated. At one point, she says, "Every step I take is another step toward something amazing!" This statement comes just before they trip on a root and stumble into a muddy ditch.

The author uses Clara's optimistic declaration in a context that ultimately contradicts her experience. What type of irony is demonstrated in this passage?