Fix copying hashmaps

- len == 0 wasn't handled propery
- Incorrect source k/v address
- New object was never returned m(

src/hashmap.c

@@ -341,6 +341,10 @@ apfl_hashmap_copy(apfl_hashmap src)
         struct bucket *dstbucket = &dst->buckets[i];
         size_t len = srcbucket->len;
 
+        if (len == 0) {
+            continue;
+        }
+
         dstbucket->keys = malloc(keysize * len);
         dstbucket->values = malloc(valsize * len);
         if (dstbucket->keys == NULL || dstbucket->values == NULL) {
@@ -354,23 +358,25 @@ apfl_hashmap_copy(apfl_hashmap src)
 
         dstbucket->cap = len;
 
-        for (; dstbucket->len < len; dstbucket->len++) {
-            void *keyaddr = KVADDR(dstbucket->keys, keysize, dstbucket->len);
-
+        for (size_t j = 0; j < len; j++) {
             copy_key(
                 dst,
-                keyaddr,
-                KVADDR(srcbucket->keys, keysize, srcbucket->len)
+                KVADDR(dstbucket->keys, keysize, j),
+                KVADDR(srcbucket->keys, keysize, j)
             );
 
             copy_value(
                 dst,
-                KVADDR(dstbucket->values, valsize, dstbucket->len),
-                KVADDR(srcbucket->values, valsize, srcbucket->len)
+                KVADDR(dstbucket->values, valsize, j),
+                KVADDR(srcbucket->values, valsize, j)
             );
+
+            dstbucket->len++;
         }
     }
 
+    return dst;
+
 fail:
     apfl_hashmap_destroy(dst);
     return NULL;