Fixed index out of range issue when event contains a trailing %n

Author: jschick04

src/EventLogExpert.Eventing.Tests/EventResolvers/EventResolverBaseTests.cs

@@ -170,6 +170,45 @@ public void ResolveEvent_WithFormattingCharacters_ShouldCleanupDescription()
         Assert.Contains("\t", displayEvent.Description);
     }
 
+    [Fact]
+    public void ResolveEvent_WithTrailingPercentN_ShouldNotThrowIndexOutOfRange()
+    {
+        // Arrange
+        var providerDetails = new ProviderDetails
+        {
+            ProviderName = Constants.TestProviderName,
+            Events = [],
+            Messages =
+            [
+                new MessageModel
+                {
+                    ProviderName = Constants.TestProviderName,
+                    ShortId = 1001,
+                    Text = "Message ends with newline%n"
+                }
+            ],
+            Parameters = [],
+            Keywords = new Dictionary<long, string>(),
+            Tasks = new Dictionary<int, string>()
+        };
+
+        var resolver = new TestEventResolver([providerDetails]);
+
+        var eventRecord = new EventRecord
+        {
+            ProviderName = Constants.TestProviderName,
+            Id = 1001,
+            Properties = []
+        };
+
+        // Act - should not throw IndexOutOfRangeException
+        var displayEvent = resolver.ResolveEvent(eventRecord);
+
+        // Assert
+        Assert.NotNull(displayEvent);
+        Assert.EndsWith("\r\n", displayEvent.Description);
+    }
+
     [Fact]
     public void ResolveEvent_WithHexPropertyType_ShouldFormatAsHex()
     {

src/EventLogExpert.Eventing/EventResolvers/EventResolverBase.cs

@@ -134,18 +134,18 @@ private static void CleanupFormatting(ReadOnlySpan<char> unformattedString, ref
             switch (unformattedString[i])
             {
                 case '%' when i + 1 < unformattedString.Length:
-                    switch (unformattedString[i + 1])
-                    {
-                        case 'n':
-                            if (unformattedString[i + 2] != '\r')
-                            {
-                                buffer[bufferIndex++] = '\r';
-                                buffer[bufferIndex++] = '\n';
-                            }
+                        switch (unformattedString[i + 1])
+                        {
+                            case 'n':
+                                if (i + 2 >= unformattedString.Length || unformattedString[i + 2] != '\r')
+                                {
+                                    buffer[bufferIndex++] = '\r';
+                                    buffer[bufferIndex++] = '\n';
+                                }
 
-                            i++;
+                                i++;
 
-                            break;
+                                break;
                         case 't':
                             buffer[bufferIndex++] = '\t';
                             i++;