...

runtime/ref.c

@@ -7,6 +7,7 @@ void *rc_alloc(size_t size, void (*destructor)(void *self))
 {
     printf("rc_alloc %zu bytes\n", size);
     ref_header *header = malloc(sizeof(ref_header) + size);
+    memset(header, 0, size);
     if (!header)
     {
         exit(69);
@@ -20,6 +21,9 @@ void *rc_alloc(size_t size, void (*destructor)(void *self))
 
 void rc_retain(void *obj)
 {
+    if (!obj)
+        return;
+
     printf("rc_retain\n");
     ref_header *header = ((ref_header *)obj) - 1;
     header->ref_count++;
@@ -27,6 +31,9 @@ void rc_retain(void *obj)
 
 void rc_release(void *obj)
 {
+    if (!obj)
+        return;
+
     ref_header *header = ((ref_header *)obj) - 1;
     printf("rc_release\n");
     if (--header->ref_count == 0)