Raise instead of logging

lib/explorer/backend/lazy_series.ex

@@ -6,7 +6,6 @@ defmodule Explorer.Backend.LazySeries do
   """
   alias Explorer.Series
   alias Explorer.Backend
-  require Logger
 
   @behaviour Explorer.Backend.Series
 
@@ -1197,25 +1196,17 @@ defmodule Explorer.Backend.LazySeries do
   def re_named_captures(series, pattern) do
     lazy_s = lazy_series!(series)
 
-    target_dtype = get_backend(lazy_s).re_dtype(pattern)
+    backend = get_backend(lazy_s, "re_named_captures/2")
+    target_dtype = backend.re_dtype(pattern)
 
     data = new(:re_named_captures, [lazy_s, pattern], target_dtype)
 
     Backend.Series.new(data, target_dtype)
   end
 
-  defp get_backend(%__MODULE__{} = lazy_series) do
-    lazy_series.backend || warning_with_default_backend()
-  end
-
-  defp warning_with_default_backend do
-    backend = Explorer.Backend.get()
-
-    Logger.warning(
-      "cannot get backend from LazySeries. Using the default one: #{inspect(backend)}"
-    )
-
-    :"#{backend}.DataFrame"
+  defp get_backend(%__MODULE__{} = lazy_series, function) do
+    lazy_series.backend ||
+      raise "cannot get backend from Explorer.Backend.LazySeries for `#{function}`"
   end
 
   @remaining_non_lazy_operations [