fix(tensorflow-backend): Fix asarray in tensorflow backend for cases …

…when dtype is not provided and the passed in object is also not a tf.Tensor

ivy/functional/backends/tensorflow/creation.py

@@ -93,9 +93,12 @@ def asarray(
     with tf.device(device):
         if tf.is_tensor(obj):
             ret = tf.cast(obj, dtype) if obj.dtype != dtype else obj
-        elif dtype.is_integer and np.issubdtype(
-            (obj_np := np.array(obj)).dtype, np.floating
+        elif (
+            dtype is not None
+            and dtype.is_integer
+            and np.issubdtype(np.array(obj).dtype, np.floating)
         ):
+            obj_np = np.array(obj)
             ret = tf.convert_to_tensor(obj_np, dtype)
         else:
             ret = tf.convert_to_tensor(obj, dtype)