docs: clarify try_cmp behavior for NULL inputs

Author: Brijesh-Thakkar

datafusion/common/src/scalar/mod.rs

@@ -4021,11 +4021,15 @@ impl ScalarValue {
         arr1 == &right
     }
 
-    /// Compare `self` with `other` and return an `Ordering`.
+   /// Compare two `ScalarValue`s.
     ///
-    /// This is the same as [`PartialOrd`] except that it returns
-    /// `Err` if the values cannot be compared, e.g., they have incompatible data types.
-    pub fn try_cmp(&self, other: &Self) -> Result<Ordering> {
+    /// Returns an error if:
+    /// * the values are of incompatible types, or
+    /// * either value is NULL.
+    ///
+    /// This differs from `partial_cmp`, which returns `None` for NULL inputs
+    /// instead of an error.
+        pub fn try_cmp(&self, other: &Self) -> Result<Ordering> {
         self.partial_cmp(other).ok_or_else(|| {
             _internal_datafusion_err!("Uncomparable values: {self:?}, {other:?}")
         })