Store error as a simple string, not a list, when a postgrex_error

Author: acco

lib/sequin/error.ex

@@ -213,8 +213,7 @@ defmodule Sequin.Error do
     def from_postgrex(summary_prefix, %Postgrex.Error{} = error) do
       pg_code = error.postgres && error.postgres.code
       message = error.message || (error.postgres && error.postgres.message)
-      # Use a list so it's JSON-encodeable
-      code = if pg_code, do: [:postgrex_error, pg_code], else: :postgrex_error
+      code = if pg_code, do: "postgrex_error:#{pg_code}", else: "postgrex_error"
 
       %__MODULE__{
         errors: %{},