Improve role error message handling and display

BirthdayBot/BackgroundWorker.vb

@@ -121,12 +121,19 @@ Class BackgroundWorker
         Dim announceNames As IEnumerable(Of SocketGuildUser)
         Try
             announceNames = Await BirthdayApplyAsync(guild, role, birthdays)
-        Catch ex As Exception
             SyncLock _bot.KnownGuilds
-                ' Failed to apply role. Reset the warning.
+                _bot.KnownGuilds(guild.Id).RoleWarning = False
+            End SyncLock
+        Catch ex As Discord.Net.HttpException
+            If ex.HttpCode = HttpStatusCode.Forbidden Then
+                SyncLock _bot.KnownGuilds
+                    ' Failed to apply role. Set the warning.
                     _bot.KnownGuilds(guild.Id).RoleWarning = True
                 End SyncLock
                 Return 0
+            End If
+
+            Throw
         End Try
         If announceNames.Count <> 0 Then
             ' Send out announcement message

BirthdayBot/Data/GuildSettings.vb

@@ -18,11 +18,12 @@ Friend Class GuildSettings
 
     Private _roleWarning As Boolean
     Private _roleLastWarning As New DateTimeOffset(DateTime.MinValue, TimeSpan.Zero)
-    Private Shared ReadOnly RoleWarningInterval As New TimeSpan(0, 10, 0)
+    Private Shared ReadOnly RoleWarningInterval As New TimeSpan(1, 0, 0)
 
     ''' <summary>
     ''' Flag for notifying servers that the bot is unable to manipulate its role.
-    ''' Can be set at any time. Reading this will only return True once every 10 minutes, if at all.
+    ''' Can be set at any time. Reading this will only return True if it's been set as such,
+    ''' and it is only returned after a set time has passed in order to not constantly show the message.
     ''' </summary>
     Public Property RoleWarning As Boolean
         Get