Cancel early when rate limited

PluralKit.Bot/Services/WebhookExecutorService.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Net;
 using System.Net.Http;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
@@ -74,6 +75,10 @@ namespace PluralKit.Bot
             using var response = await _client.PostAsync($"{DiscordConfig.APIUrl}webhooks/{webhook.Id}/{webhook.Token}?wait=true", mfd);
             timerCtx.Dispose();
 
+            if (response.StatusCode == HttpStatusCode.TooManyRequests)
+                // Rate limits should be respected, we bail early
+                throw new WebhookExecutionErrorOnDiscordsEnd();
+
             var responseString = await response.Content.ReadAsStringAsync();
 
             JObject responseJson;