Fix Arena realloc bug

src/arena_allocator.cpp

@@ -77,11 +77,7 @@ void *ArenaAllocator::realloc_raw(void *ptr, uint32_t old_size,
   assert(current_block_ &&
          "realloc called with non-null ptr but no current block exists");
 
-  // Assert that offset is large enough (should always be true for
-  // valid callers)
-  assert(current_block_->offset >= old_size &&
-         "offset must be >= old_size for valid last allocation");
-
+  if (current_block_->offset >= old_size) {
     // Check if this was the last allocation by comparing with expected location
     char *expected_last_alloc_start =
         current_block_->data() + current_block_->offset - old_size;
@@ -105,6 +101,7 @@ void *ArenaAllocator::realloc_raw(void *ptr, uint32_t old_size,
         return new_size == 0 ? nullptr : ptr;
       }
     }
+  }
 
   // Can't extend in place
   if (new_size == 0) {