1 files changed, 19 insertions, 3 deletions
diff --git a/src/SMAPI.Web/BackgroundService.cs b/src/SMAPI.Web/BackgroundService.cs
index 64bd5ca5..49356f76 100644
--- a/src/SMAPI.Web/BackgroundService.cs
+++ b/src/SMAPI.Web/BackgroundService.cs
@@ -19,13 +19,17 @@ namespace StardewModdingAPI.Web
         ** Fields
         *********/
         /// <summary>The background task server.</summary>
-        private static BackgroundJobServer JobServer;
+        private static BackgroundJobServer? JobServer;
 
         /// <summary>The cache in which to store wiki metadata.</summary>
-        private static IWikiCacheRepository WikiCache;
+        private static IWikiCacheRepository? WikiCache;
 
         /// <summary>The cache in which to store mod data.</summary>
-        private static IModCacheRepository ModCache;
+        private static IModCacheRepository? ModCache;
+
+        /// <summary>Whether the service has been started.</summary>
+        [MemberNotNullWhen(true, nameof(BackgroundService.JobServer), nameof(BackgroundService.WikiCache), nameof(BackgroundService.ModCache))]
+        private static bool IsStarted { get; set; }
 
 
         /*********
@@ -59,6 +63,8 @@ namespace StardewModdingAPI.Web
             RecurringJob.AddOrUpdate(() => BackgroundService.UpdateWikiAsync(), "*/10 * * * *"); // every 10 minutes
             RecurringJob.AddOrUpdate(() => BackgroundService.RemoveStaleModsAsync(), "0 * * * *"); // hourly
 
+            BackgroundService.IsStarted = true;
+
             return Task.CompletedTask;
         }
 
@@ -66,6 +72,8 @@ namespace StardewModdingAPI.Web
         /// <param name="cancellationToken">Tracks whether the shutdown process should no longer be graceful.</param>
         public async Task StopAsync(CancellationToken cancellationToken)
         {
+            BackgroundService.IsStarted = false;
+
             if (BackgroundService.JobServer != null)
                 await BackgroundService.JobServer.WaitForShutdownAsync(cancellationToken);
         }
@@ -73,6 +81,8 @@ namespace StardewModdingAPI.Web
         /// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
         public void Dispose()
         {
+            BackgroundService.IsStarted = false;
+
             BackgroundService.JobServer?.Dispose();
         }
 
@@ -83,6 +93,9 @@ namespace StardewModdingAPI.Web
         [AutomaticRetry(Attempts = 3, DelaysInSeconds = new[] { 30, 60, 120 })]
         public static async Task UpdateWikiAsync()
         {
+            if (!BackgroundService.IsStarted)
+                throw new InvalidOperationException($"Must call {nameof(BackgroundService.StartAsync)} before scheduling tasks.");
+
             WikiModList wikiCompatList = await new ModToolkit().GetWikiCompatibilityListAsync();
             BackgroundService.WikiCache.SaveWikiData(wikiCompatList.StableVersion, wikiCompatList.BetaVersion, wikiCompatList.Mods);
         }
@@ -90,6 +103,9 @@ namespace StardewModdingAPI.Web
         /// <summary>Remove mods which haven't been requested in over 48 hours.</summary>
         public static Task RemoveStaleModsAsync()
         {
+            if (!BackgroundService.IsStarted)
+                throw new InvalidOperationException($"Must call {nameof(BackgroundService.StartAsync)} before scheduling tasks.");
+
             BackgroundService.ModCache.RemoveStaleMods(TimeSpan.FromHours(48));
             return Task.CompletedTask;
         }