Force enumeration of global collections before using them (#106)

This PR closes #105 

This PR fixes exceptions caused by changing a collection's contents
while it is being enumerated. This can often happen with Guild- and
MemberDatas. By using `ToArray()` on these global collections and using
it in the `foreach` loop, we create a new copy of the collection,
preventing any modification to it.

While this does introduce a lot of memory allocations, there is no
fixing that. Usually, the fix to these exceptions would be to convert
the `foreach` to a reverse-`for`. However, because indices cannot be
used on these collections, that is not possible.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

src/Commands/RemindCommandGroup.cs

@@ -85,7 +85,7 @@ public class RemindCommandGroup : CommandGroup
         }
 
         var builder = new StringBuilder();
-        for (var i = 0; i < data.Reminders.Count; i++)
+        for (var i = data.Reminders.Count - 1; i >= 0; i--)
         {
             var reminder = data.Reminders[i];
             builder.AppendLine(
@@ -168,8 +168,7 @@ public class RemindCommandGroup : CommandGroup
     [RequireContext(ChannelContext.Guild)]
     [UsedImplicitly]
     public async Task<Result> ExecuteDeleteReminderAsync(
-        [Description("Index of reminder to delete")]
-        [MinValue(0)]
+        [Description("Index of reminder to delete")] [MinValue(0)]
         int index)
     {
         if (!_context.TryGetContextIDs(out var guildId, out _, out var userId))

src/Services/GuildDataService.cs

@@ -46,7 +46,8 @@ public sealed class GuildDataService : IHostedService
     {
         _logger.LogInformation("Saving guild data...");
         var tasks = new List<Task>();
-        foreach (var data in _datas.Values)
+        var datas = _datas.Values.ToArray();
+        foreach (var data in datas)
         {
             await using var settingsStream = File.Create(data.SettingsPath);
             tasks.Add(JsonSerializer.SerializeAsync(settingsStream, data.Settings, cancellationToken: ct));
@@ -54,7 +55,8 @@ public sealed class GuildDataService : IHostedService
             await using var eventsStream = File.Create(data.ScheduledEventsPath);
             tasks.Add(JsonSerializer.SerializeAsync(eventsStream, data.ScheduledEvents, cancellationToken: ct));
 
-            foreach (var memberData in data.MemberData.Values)
+            var memberDatas = data.MemberData.Values.ToArray();
+            foreach (var memberData in memberDatas)
             {
                 await using var memberDataStream = File.Create($"{data.MemberDataPath}/{memberData.Id}.json");
                 tasks.Add(JsonSerializer.SerializeAsync(memberDataStream, memberData, cancellationToken: ct));

src/Services/Update/MemberUpdateService.cs

@@ -63,7 +63,8 @@ public sealed partial class MemberUpdateService : BackgroundService
         var guildData = await _guildData.GetData(guildId, ct);
         var defaultRole = GuildSettings.DefaultRole.Get(guildData.Settings);
         var failedResults = new List<Result>();
-        foreach (var data in guildData.MemberData.Values)
+        var memberDatas = guildData.MemberData.Values.ToArray();
+        foreach (var data in memberDatas)
         {
             var tickResult = await TickMemberDataAsync(guildId, guildData, defaultRole, data, ct);
             failedResults.AddIfFailed(tickResult);