vm: gracefully handle unresolved upvalues

Upcoming module support will rely on upresolved upvalues which are patched
at runtime to realize module imports, make sure the VM trace code does not
choke on such unresolved upvalues.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 4 insertions, 1 deletions

diff --git a/vm.c b/vm.c
index 0529ee3..d0fe80e 100644
--- a/vm.c
+++ b/vm.c
@@ -345,7 +345,10 @@ uc_vm_frame_dump(uc_vm_t *vm, uc_callframe_t *frame)
 			fprintf(stderr, "     [%zu] <%p> %s ",
 				i, (void *)ref, uc_vm_format_val(vm, v));
 
-			if (ref->closed) {
+			if (!ref) {
+				fprintf(stderr, "{unresolved}\n");
+			}
+			else if (ref->closed) {
 				fprintf(stderr, "{closed} %s\n",
 					uc_vm_format_val(vm, ref->value));
 			}