Fixing a bug introduced by one of the fixes (#1421)

Author: belav

Src/CSharpier.Tests/FormattingTests/TestFiles/cs/Comments_EndOfFileWithDirective.expected.test

@@ -0,0 +1,4 @@
+// Some Comment
+
+#if DEBUG
+#endif

Src/CSharpier.Tests/FormattingTests/TestFiles/cs/Comments_EndOfFileWithDirective.test

@@ -0,0 +1,5 @@
+
+// Some Comment
+
+#if DEBUG
+#endif

Src/CSharpier/SyntaxPrinter/SyntaxNodePrinters/CompilationUnit.cs

@@ -18,7 +18,8 @@ public static Doc Print(CompilationUnitSyntax node, PrintingContext context)
             if (
                 finalTrivia is Concat { Contents.Count: > 1 } list
                 && list.Contents[1] is LeadingComment
-                && docs[^1] is Concat previousList
+                && docs.Count > 0
+                && docs[^1] is Concat { Contents.Count: > 1 } previousList
                 && previousList.Contents[^1] is HardLine
                 && previousList.Contents[^2] is HardLine
             )