fix FixedArray::get and corresponding doc test

builtin/builtin.mbti

@@ -517,8 +517,7 @@ fn FixedArray::blit_from_bytes(Self[Byte], Int, Bytes, Int, Int) -> Unit
 fn FixedArray::blit_from_string(Self[Byte], Int, String, Int, Int) -> Unit
 fn[A] FixedArray::blit_to(Self[A], Self[A], len~ : Int, src_offset~ : Int = .., dst_offset~ : Int = ..) -> Unit
 fn[T] FixedArray::fill(Self[T], T) -> Unit
-#deprecated
-fn[T] FixedArray::get(Self[T], Int) -> T
+fn[T] FixedArray::get(Self[T], Int) -> T?
 fn[T] FixedArray::is_empty(Self[T]) -> Bool
 fn[T] FixedArray::iter(Self[T]) -> Iter[T]
 fn[T] FixedArray::iter2(Self[T]) -> Iter2[Int, T]

builtin/fixedarray.mbt

@@ -12,6 +12,36 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+///|
+/// Retrieves an element at the specified index from a fixed-size array. 
+///
+/// Parameters:
+///
+/// * `array` : The fixed-size array to access.
+/// * `index` : The position in the array from which to retrieve the element.
+///
+/// Returns `Some(element)` if the index is within bounds, or `None` if the index
+/// is out of bounds.
+///
+/// Example:
+///
+/// ```moonbit
+/// test "FixedArray::get" {
+///   let arr : FixedArray[Int] = [1, 2, 3]
+///   inspect!(arr.get(1), content="Some(2)")
+/// }
+///
+/// test "FixedArray::get/out_of_bounds" {
+///   let arr : FixedArray[Int] = [1, 2, 3]
+///   inspect!(arr.get(3), content="None")
+/// }
+/// ```
+pub fn[T] FixedArray::get(self : FixedArray[T], idx : Int) -> T? {
+  let len = self.length()
+  guard idx >= 0 && idx < len else { None }
+  Some(self.unsafe_get(idx))
+}
+
 ///|
 ///
 /// Creates an iterator over the elements of a fixed-size array, providing

builtin/intrinsics.mbt

@@ -1554,36 +1554,6 @@ pub fn[T] FixedArray::unsafe_set(
   val : T
 ) -> Unit = "%fixedarray.unsafe_set"
 
-///|
-/// Retrieves an element at the specified index from a fixed-size array. This
-/// function is similar to `op_get` but provides explicit bounds checking.
-///
-/// Parameters:
-///
-/// * `array` : The fixed-size array to access.
-/// * `index` : The position in the array from which to retrieve the element.
-///
-/// Returns the element at the specified index.
-///
-/// Throws a runtime error if the index is out of bounds (less than 0 or greater
-/// than or equal to the length of the array).
-///
-/// Example:
-///
-/// ```moonbit
-/// test "FixedArray::get" {
-///   let arr = [1, 2, 3]
-///   inspect(arr.get(1), content="Some(2)")
-/// }
-///
-/// test "FixedArray::get/out_of_bounds" {
-///   let arr = [1, 2, 3]
-///   inspect(arr.get(3), content="None")
-/// }
-/// ```
-#deprecated("use `arr.op_get(i)`(arr[i]) instead")
-pub fn[T] FixedArray::get(self : FixedArray[T], idx : Int) -> T = "%fixedarray.get"
-
 ///|
 /// Sets a value at the specified index in a fixed-size array. The original value
 /// at that index is overwritten.