From 6aa9bd8e5e1b22b25ef3a273c67107b23636dcc6 Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Thu, 4 Sep 2025 22:37:03 +0200
Subject: [PATCH] Fix #3549: Do not crash on encountering nil tokens.

---
 ICSharpCode.Decompiler/IL/ILReader.cs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/ICSharpCode.Decompiler/IL/ILReader.cs b/ICSharpCode.Decompiler/IL/ILReader.cs
index 9e6236a89..072943ebd 100644
--- a/ICSharpCode.Decompiler/IL/ILReader.cs
+++ b/ICSharpCode.Decompiler/IL/ILReader.cs
@@ -212,7 +212,14 @@ namespace ICSharpCode.Decompiler.IL
 				// Row-IDs < 1 are always invalid.
 				throw new BadImageFormatException("Invalid metadata token");
 			}
-			return MetadataTokens.EntityHandle(token);
+			var handle = MetadataTokens.EntityHandle(token);
+			if (handle.IsNil)
+			{
+				// The runtime will crash with a BadImageFormatException when it encounters a row-ID of 0.
+				// We assume the code following this instruction to be unreachable.
+				throw new BadImageFormatException("Invalid metadata token");
+			}
+			return handle;
 		}
 
 		IType ReadAndDecodeTypeReference()