Fix bug when loading heap

Need to grow as needed.

include/vm/heap.h

@@ -50,6 +50,7 @@ extern size_t heap_size;
 
 void heap_init(void);
 void heap_delete(void);
+void heap_grow(size_t new_size);
 
 int32_t heap_alloc_slot(enum vm_pointer_type type);
 void heap_ref(int slot);

src/heap.c

@@ -18,6 +18,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <assert.h>
 #include "system4/string.h"
 #include "vm.h"
 #include "vm/heap.h"
@@ -45,8 +46,9 @@ static const char *vm_ptrtype_string(enum vm_pointer_type type) {
 	return "INVALID POINTER TYPE";
 }
 
-static void heap_grow(size_t new_size)
+void heap_grow(size_t new_size)
 {
+	assert(new_size > heap_size);
 	heap = xrealloc(heap, sizeof(struct vm_pointer) * new_size);
 	heap_free_stack = xrealloc(heap_free_stack, sizeof(int32_t) * new_size);
 	for (size_t i = heap_size; i < new_size; i++) {

src/resume.c

@@ -256,6 +256,9 @@ static void delete_heap(void)
 //      Out-of-order allocations would break the above assumption!
 static void alloc_heap_slot(int slot)
 {
+	if ((size_t)slot >= heap_size) {
+		heap_grow(heap_size * 2);
+	}
 	heap_free_stack[slot] = heap_free_stack[heap_free_ptr];
 	heap_free_ptr++;
 }