Fix undefined identifier error for generic instance used as bind target

[taichi-ishitani]

fix #1896

[codspeed-hq]

CodSpeed Performance Report

Merging #1897 will not alter performance

_{Comparing taichi-ishitani:fix_undefined_identifier (ff1b913) with master (98d95ca)¹}

Summary

✅ 3 untouched benchmarks

Footnotes

1. No successful run was found on master (d9131c4) during the generation of this report, so 98d95ca was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩