Epic: Error messages + linting

We could spend some time improving our error messages. (This statement is always true, but there are a number of specific things we could focus on).

• https://github.com/quarto-dev/quarto-cli/issues/1570
• https://github.com/quarto-dev/quarto-cli/issues/4782
• #8723
• #8765
• #6929
• https://github.com/quarto-dev/quarto-cli/issues/4938
• #5397
• #8922
• https://github.com/quarto-dev/quarto-cli/issues/4782
• https://github.com/quarto-dev/quarto-cli/issues/9512
• https://github.com/quarto-dev/quarto-cli/issues/8953
• #9441
• #10106
• #10185 (warn when computational code cell isn't supported by the engine)
• #10305
• #10537

Validation

• https://github.com/quarto-dev/quarto-cli/issues/1794
• #8762

Linting

• #7975
• #7552
• #7157
• #6962
• #6826
• #6594
• #6328
• #5978
• #5767
• #5571
• #5182
• #4751
• #4740
• #4542
• #4011
• #3900
• #3560
• #3004
• #2769
• #385
• #4291
• #4150
• #3371
• #8804
• #8386
• #7307
• https://github.com/quarto-dev/quarto-cli/issues/2140
• https://github.com/quarto-dev/quarto-cli/discussions/10012
• #10103
• #11021
• #12972

See Mine's framing here: messages as a call to attention, warnings as a call to action.

Start by reviewing the linked error-message, validation, and linting issues, including the checked item #10537 and the referenced discussion on messages and warnings. The epic is complete when its selected child issues have been resolved and the checklist reflects their status.