Fix usage of is_bitstring instead of is_binary

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/graphql/resolvers/admin.ex

@@ -321,7 +321,7 @@ defmodule Mobilizon.GraphQL.Resolvers.Admin do
       {:ok, _activity, follow} ->
         {:ok, follow}
 
-      {:error, {:error, err}} when is_bitstring(err) ->
+      {:error, {:error, err}} when is_binary(err) ->
         {:error, err}
     end
   end
@@ -336,7 +336,10 @@ defmodule Mobilizon.GraphQL.Resolvers.Admin do
       {:ok, _activity, follow} ->
         {:ok, follow}
 
-      {:error, {:error, err}} when is_bitstring(err) ->
+      {:error, {:error, err}} when is_binary(err) ->
+        {:error, err}
+
+      {:error, err} when is_binary(err) ->
         {:error, err}
     end
   end
@@ -351,7 +354,10 @@ defmodule Mobilizon.GraphQL.Resolvers.Admin do
       {:ok, _activity, follow} ->
         {:ok, follow}
 
-      {:error, {:error, err}} when is_bitstring(err) ->
+      {:error, {:error, err}} when is_binary(err) ->
+        {:error, err}
+
+      {:error, err} when is_binary(err) ->
         {:error, err}
     end
   end

lib/graphql/resolvers/participant.ex

@@ -264,7 +264,7 @@ defmodule Mobilizon.GraphQL.Resolvers.Participant do
   @spec valid_email?(String.t() | nil) :: boolean
   defp valid_email?(email) when is_nil(email), do: false
 
-  defp valid_email?(email) when is_bitstring(email) do
+  defp valid_email?(email) when is_binary(email) do
     email
     |> String.trim()
     |> Checker.valid?()