Make 'additional_fields' optional in JSON error template functions

This allows us to de-duplicate functions

src/invidious/helpers/errors.cr

@@ -129,7 +129,12 @@ macro error_json(*args)
   error_json_helper(env, {{*args}})
 end
 
-def error_json_helper(env : HTTP::Server::Context, status_code : Int32, exception : Exception, additional_fields : Hash(String, Object) | Nil)
+def error_json_helper(
+  env : HTTP::Server::Context,
+  status_code : Int32,
+  exception : Exception,
+  additional_fields : Hash(String, Object) | Nil = nil
+)
   if exception.is_a?(InfoException)
     return error_json_helper(env, status_code, exception.message || "", additional_fields)
   end
@@ -146,11 +151,12 @@ def error_json_helper(env : HTTP::Server::Context, status_code : Int32, exceptio
   return error_message.to_json
 end
 
-def error_json_helper(env : HTTP::Server::Context, status_code : Int32, exception : Exception)
-  return error_json_helper(env, status_code, exception, nil)
-end
-
-def error_json_helper(env : HTTP::Server::Context, status_code : Int32, message : String, additional_fields : Hash(String, Object) | Nil)
+def error_json_helper(
+  env : HTTP::Server::Context,
+  status_code : Int32,
+  message : String,
+  additional_fields : Hash(String, Object) | Nil = nil
+)
   env.response.content_type = "application/json"
   env.response.status_code = status_code
 
@@ -163,10 +169,6 @@ def error_json_helper(env : HTTP::Server::Context, status_code : Int32, message
   return error_message.to_json
 end
 
-def error_json_helper(env : HTTP::Server::Context, status_code : Int32, message : String)
-  error_json_helper(env, status_code, message, nil)
-end
-
 # -------------------
 #  Redirect
 # -------------------