More helpful error messages when YAML-writing agents/informants with a non-lazy tbl

[yjunechoe]

Summary

write_yaml() now uses information in $tbl_name to construct more informative error messages when the tbl is not supplied lazily upon agent/informant's creation (requirement for yaml-writing).

Special error msg if tbl was supplied as a variable (hint to use ~):

create_agent(small_table) %>% 
  yaml_write()
#> Error:
#> ✖ The agent must have a `tbl` value that can be put into YAML.
#> ℹ Did you mean to pass the table lazily? Ex: `create_agent(tbl = ~ small_table)`

Generic error msg if tbl was supplied as a complex expression (points to yaml_write()):

create_agent(small_table %>% head(1)) %>% 
  yaml_write()
#> Error:
#> ✖ The agent must have a `tbl` value that can be put into YAML.
#> ℹ See `?yaml_write` for details.

This behavior has been united across agents and informants via a helper function check_lazy_tbl()

Related GitHub Issues and PRs

• Ref: Cannot export informants to YAML #596

Checklist

• I understand and agree to the Code of Conduct.
• I have listed any major changes in the NEWS.
• I have added testthat unit tests to tests/testthat for any new functionality.

[rich-iannone]

Thank you so much for this PR and for handling the underlying issue so well! Will review this in short order :)

[rich-iannone]

LGTM!

[rich-iannone]

PR is awesome (as expected!). Merge anytime!