fix(explore): handle cursor size zero using saturating_sub

crates/nu-explore/src/views/cursor/mod.rs

@@ -36,7 +36,7 @@ impl Cursor {
 
     /// The max position the cursor can be at
     pub fn end(&self) -> usize {
-        self.size - 1
+        self.size.saturating_sub(1)
     }
 
     /// Set the position to a specific value within the bounds [0, end]
@@ -121,4 +121,28 @@ mod tests {
         cursor.move_backward(3);
         assert_eq!(cursor.position, 0);
     }
+
+    #[test]
+    fn test_cursor_size_zero_handling() {
+       
+        let cursor = Cursor::new(0);
+        assert_eq!(cursor.end(), 0);
+        
+        let mut cursor = Cursor::new(0);
+        cursor.move_forward(1); 
+        assert_eq!(cursor.position, 0);
+        
+        cursor.move_backward(1);
+        assert_eq!(cursor.position, 0);
+    }
+
+    #[test]
+    fn test_cursor_size_one() {
+        let mut cursor = Cursor::new(1);
+        assert_eq!(cursor.end(), 0);
+        
+        cursor.move_forward(1);
+        assert_eq!(cursor.position, 0);
+    }
+    
 }