Improve Rojo sync reliability (#739)

Uses non-recursive main loop and avoids hanging promises

plugin/src/ApiContext.lua

@@ -11,13 +11,6 @@ local validateApiInfo = Types.ifEnabled(Types.ApiInfoResponse)
 local validateApiRead = Types.ifEnabled(Types.ApiReadResponse)
 local validateApiSubscribe = Types.ifEnabled(Types.ApiSubscribeResponse)
 
---[[
-	Returns a promise that will never resolve nor reject.
-]]
-local function hangingPromise()
-	return Promise.new(function() end)
-end
-
 local function rejectFailedRequests(response)
 	if response.code >= 400 then
 		local message = string.format("HTTP %s:\n%s", tostring(response.code), response.body)
@@ -212,12 +205,8 @@ function ApiContext:retrieveMessages()
 	local function sendRequest()
 		local request = Http.get(url)
 			:catch(function(err)
-				if err.type == Http.Error.Kind.Timeout then
-					if self.__connected then
-						return sendRequest()
-					else
-						return hangingPromise()
-					end
+				if err.type == Http.Error.Kind.Timeout and self.__connected then
+					return sendRequest()
 				end
 
 				return Promise.reject(err)