Skip null loggers when creating loggers in Logger factory.

Author: petrroll

src/libraries/Microsoft.Extensions.Logging/src/LoggerFactory.cs

@@ -8,6 +8,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.Extensions.Logging
@@ -211,12 +212,19 @@ private void AddProviderRegistration(ILoggerProvider provider, bool dispose)
 
         private LoggerInformation[] CreateLoggers(string categoryName)
         {
-            var loggers = new LoggerInformation[_providerRegistrations.Count];
+            var loggers = new List<LoggerInformation>(_providerRegistrations.Count);
             for (int i = 0; i < _providerRegistrations.Count; i++)
             {
-                loggers[i] = new LoggerInformation(_providerRegistrations[i].Provider, categoryName);
+                var loggerInformation = new LoggerInformation(_providerRegistrations[i].Provider, categoryName);
+
+                // We do not need to check for NullLogger<T>.Instance as no provider would reasonably return it (the <T> handling is at
+                // outer loggers level, not inner level loggers in Logger/LoggerProvider).
+                if (loggerInformation.Logger != NullLogger.Instance)
+                {
+                    loggers.Add(loggerInformation);
+                }
             }
-            return loggers;
+            return [..loggers];
         }
 
         private (MessageLogger[] MessageLoggers, ScopeLogger[]? ScopeLoggers) ApplyFilters(LoggerInformation[] loggers)
@@ -237,6 +245,14 @@ private LoggerInformation[] CreateLoggers(string categoryName)
                     continue;
                 }
 
+                var logger = loggerInformation.Logger;
+                if (logger is NullLogger ||
+                    (logger.GetType() is var loggerType && loggerType.IsGenericType && loggerType.GetGenericTypeDefinition() == typeof(NullLogger<>)))
+                {
+                    // Skip NullLogger instances
+                    continue;
+                }
+
                 messageLoggers.Add(new MessageLogger(loggerInformation.Logger, loggerInformation.Category, loggerInformation.ProviderType.FullName, minLevel, filter));
 
                 if (!loggerInformation.ExternalScope)