Do not crash on files that contain no managed metadata.

ICSharpCode.Decompiler/Metadata/EnumUnderlyingTypeResolveException.cs

@@ -23,22 +23,25 @@ using System.Text;
 
 namespace ICSharpCode.Decompiler.Metadata
 {
+	[Serializable]
 	public class EnumUnderlyingTypeResolveException : Exception
 	{
-		public EnumUnderlyingTypeResolveException()
-		{
-		}
-
-		public EnumUnderlyingTypeResolveException(string message) : base(message)
-		{
-		}
-
-		public EnumUnderlyingTypeResolveException(string message, Exception innerException) : base(message, innerException)
-		{
-		}
+		public EnumUnderlyingTypeResolveException() { }
+		public EnumUnderlyingTypeResolveException(string message) : base(message) { }
+		public EnumUnderlyingTypeResolveException(string message, Exception inner) : base(message, inner) { }
+		protected EnumUnderlyingTypeResolveException(
+		  SerializationInfo info,
+		  StreamingContext context) : base(info, context) { }
+	}
 
-		protected EnumUnderlyingTypeResolveException(SerializationInfo info, StreamingContext context) : base(info, context)
-		{
-		}
+	[Serializable]
+	public class PEFileNotSupportedException : Exception
+	{
+		public PEFileNotSupportedException() { }
+		public PEFileNotSupportedException(string message) : base(message) { }
+		public PEFileNotSupportedException(string message, Exception inner) : base(message, inner) { }
+		protected PEFileNotSupportedException(
+		  SerializationInfo info,
+		  StreamingContext context) : base(info, context) { }
 	}
 }

ICSharpCode.Decompiler/Metadata/PEFile.cs

@@ -62,7 +62,7 @@ namespace ICSharpCode.Decompiler.Metadata
 			this.FileName = fileName ?? throw new ArgumentNullException(nameof(fileName));
 			this.Reader = reader ?? throw new ArgumentNullException(nameof(reader));
 			if (!reader.HasMetadata)
-				throw new ArgumentException("PE file does not contain any metadata!");
+				throw new PEFileNotSupportedException("PE file does not contain any managed metadata.");
 			this.Metadata = reader.GetMetadataReader();
 		}
 

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -264,6 +264,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 					case DirectoryNotFoundException dirNotFound:
 						HandleException(dirNotFound, "The directory was not found.");
 						return;
+					case PEFileNotSupportedException notSupported:
+						HandleException(notSupported, notSupported.Message);
+						return;
 					default:
 						throw;
 				}