Make ValidateConstructor safe

ICSharpCode.Decompiler/IL/Transforms/TransformDisplayClassUsage.cs

@@ -151,6 +151,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					var result = AnalyzeVariable(v);
 					if (result == null)
 						continue;
+					context.Step($"Detected display-class {v}", result.Initializer ?? f.Body);
 					displayClasses.Add(v, result);
 				}
 			}
@@ -266,18 +267,19 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 
 		private bool ValidateConstructor(IMethod method)
 		{
+			try {
 				if (method.Parameters.Count != 0)
 					return false;
 				var handle = (MethodDefinitionHandle)method.MetadataToken;
 				var module = (MetadataModule)method.ParentModule;
 				var file = module.PEFile;
-			if (handle.IsNil || file == null)
+				if (handle.IsNil || file != context.PEFile)
 					return false;
 				var def = file.Metadata.GetMethodDefinition(handle);
 				if (def.RelativeVirtualAddress == 0)
 					return false;
 				var body = file.Reader.GetMethodBody(def.RelativeVirtualAddress);
-			if (!body.LocalSignature.IsNil)
+				if (!body.LocalSignature.IsNil || body.ExceptionRegions.Length != 0)
 					return false;
 				var reader = body.GetILReader();
 				if (reader.Length != 7)
@@ -295,9 +297,12 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				var objectCtor = module.ResolveMethod(baseCtorHandle, new TypeSystem.GenericContext());
 				if (!objectCtor.DeclaringType.IsKnownType(KnownTypeCode.Object))
 					return false;
-			if (objectCtor.Parameters.Count != 0)
+				if (!objectCtor.IsConstructor || objectCtor.Parameters.Count != 0)
 					return false;
 				return reader.DecodeOpCode() == ILOpCode.Ret;
+			} catch (BadImageFormatException) {
+				return false;
+			}
 		}
 
 		VariableToDeclare AddVariable(DisplayClass result, ILInstruction init, out IField field)
@@ -333,6 +338,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 							return declaredVar.CanPropagate;
 					}
 					return true;
+				case StLoc stloc:
+					return true;
 				default:
 					return false;
 			}