[Feature] Paper cut: include reference to execute mode check when introspective queries like run_query are skipped

[joellabes]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt functionality, rather than a Big Idea better suited to a discussion

Describe the feature

When using functions like run_query, the if execute check is necessary to avoid failures during the parse phase. Otherwise,

Any Jinja that relies on a result being returned from the database will error during the parse phase.
The error returned by dbt will look as follows:

Encountered an error:
Compilation Error in model order_payment_methods (models/order_payment_methods.sql)
  'None' has no attribute 'table'

Let's provide information about why this happened inline. Something like this:

Running dbt...

Encountered an error:
Compilation Error in model order_payment_methods (models/order_payment_methods.sql)
  'None' has no attribute 'table'
  dbt is currently not running in execute mode. You might need to wrap this code in an `if execute` block https://docs.getdbt.com/reference/dbt-jinja-functions/execute

Describe alternatives you've considered

I don't know if we actually can update the Compilation Error message with guidance because it's too late by then, so alternatively we could also add a warning line inside of run_query and friends so you wind up with something like this:

Running dbt...

WARN: run_query was invoked in the model order_payment_methods, but dbt is currently not running in execute mode so accessing the result will fail. Wrap in an `if execute` block https://docs.getdbt.com/reference/dbt-jinja-functions/execute

Encountered an error:
Compilation Error in model order_payment_methods (models/order_payment_methods.sql)
  'None' has no attribute 'table'

Who will this benefit?

Pretty much everyone who uses introspection, including:

• users getting started with dbt as recently as today
• me, 4 years ago (when I had already been using dbt for a year and really should have Known Better)

Are you interested in contributing this feature?

Maybe, if it turns out to just be "update an error message somewhere" but probably not realistically

Anything else?

No response