Fix #10868: [Script] Handle errors when loading savegame data on stack (#11029)

(cherry picked from commit 1d9bc23525)

src/script/script_instance.cpp

@@ -29,6 +29,8 @@
 #include "../fileio_func.h"
 #include "../league_type.h"
 
+#include "../3rdparty/fmt/format.h"
+
 #include "../safeguards.h"
 
 ScriptStorage::~ScriptStorage()
@@ -731,9 +733,16 @@ void ScriptInstance::LoadOnStack(ScriptData *data)
 
 	ScriptDataVariant version = data->front();
 	data->pop_front();
-	sq_pushinteger(vm, std::get<SQInteger>(version));
-	LoadObjects(vm, data);
-	this->is_save_data_on_stack = true;
+	SQInteger top = sq_gettop(vm);
+	try {
+		sq_pushinteger(vm, std::get<SQInteger>(version));
+		LoadObjects(vm, data);
+		this->is_save_data_on_stack = true;
+	} catch (Script_FatalError &e) {
+		ScriptLog::Warning(fmt::format("Loading failed: {}", e.GetErrorMessage()).c_str());
+		/* Discard partially loaded savegame data and version. */
+		sq_settop(vm, top);
+	}
 }
 
 bool ScriptInstance::CallLoad()