Use asserts in array

codegen/array/snippets/alloc_capacity

@@ -1,11 +1,7 @@
+  assert(allocator != NULL);
+
   u64 allocation_size = sizeof({ArrayType}) + item_size * capacity;
-  {ArrayType} *array   = NULL;
-
-  if (!allocator) {{
-    goto RETURN_GENERIC_ARRAY_ALLOC;
-  }}
-
-  array = wapp_mem_allocator_alloc(allocator, allocation_size);
+  {ArrayType} *array  = wapp_mem_allocator_alloc(allocator, allocation_size);
   if (!array) {{
     goto RETURN_GENERIC_ARRAY_ALLOC;
   }}