Fixed unwrap call

src/node.rs

@@ -66,11 +66,7 @@ impl Node {
     }
 
     pub fn get_character(self: &Node) -> Result<char, &str> {
-        if !self.is_leaf() {
-            return Err("This node is not a leaf node.");
-        }
-
-        Ok(self.character.unwrap())
+        self.character.ok_or("This node has no character.")
     }
 
     pub fn get_character_code(self: &Node, character: char) -> Result<BitVec, &str> {