From 19d4f63af4d4b379937762324267eeb33338a708 Mon Sep 17 00:00:00 2001
From: sluicebox <22204938+sluicebox@users.noreply.github.com>
Date: Mon, 20 Mar 2023 10:53:56 -0700
Subject: [PATCH] SCI: Fix crash in script debugger

Stepping through an instruction that accesses an invalid property caused
an error. This code is only used by the disassembler when debugging, and
the disassembler already displays when a property is invalid.
---
 engines/sci/engine/object.cpp      | 3 +--
 engines/sci/engine/scriptdebug.cpp | 8 ++++++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/engines/sci/engine/object.cpp b/engines/sci/engine/object.cpp
index 2fdbb9118f0..9dac479ba95 100644
--- a/engines/sci/engine/object.cpp
+++ b/engines/sci/engine/object.cpp
@@ -222,8 +222,7 @@ int Object::propertyOffsetToId(SegManager *segMan, int propertyOffset) const {
 	int selectors = getVarCount();
 
 	if (propertyOffset < 0 || (propertyOffset >> 1) >= selectors) {
-		error("Applied propertyOffsetToId to invalid property offset %x (property #%d not in [0..%d])",
-		          propertyOffset, propertyOffset >> 1, selectors - 1);
+		// Scripts contain instructions with invalid properties
 		return -1;
 	}
 
diff --git a/engines/sci/engine/scriptdebug.cpp b/engines/sci/engine/scriptdebug.cpp
index 16d1edb7cc7..e4ec0a88c23 100644
--- a/engines/sci/engine/scriptdebug.cpp
+++ b/engines/sci/engine/scriptdebug.cpp
@@ -316,8 +316,12 @@ reg_t disassemble(EngineState *s, reg_t pos, const Object *obj, bool printBWTag,
 			} else {
 				if (getSciVersion() == SCI_VERSION_3)
 					debugN("\t(%s)", g_sci->getKernel()->getSelectorName(param_value).c_str());
-				else
-					debugN("\t(%s)", g_sci->getKernel()->getSelectorName(obj->propertyOffsetToId(s->_segMan, param_value)).c_str());
+				else {
+					int propertySelector = obj->propertyOffsetToId(s->_segMan, param_value);
+					if (propertySelector != -1) {
+						debugN("\t(%s)", g_sci->getKernel()->getSelectorName(propertySelector).c_str());
+					}
+				}
 			}
 		}
 	}