Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

Slack thread

I accidentally included a space in my selector in Explorer: int_snowplow_unioned__core+,+ dbt_package_installs and got this first result:

When what I wanted was the intersection of the first model's children and the latter model's parents, int_snowplow_unioned__core+,+dbt_package_installs:

I would have expected dbt to let me know that model+,+ is nonsensical, because there's nothing on the right hand plus to be upstream of. I reported this as an Explorer bug but they noted it matches Core's behaviour, so now I'm here

Expected Behavior

An error to be shown that I had created an invalid selection command

Steps To Reproduce

Have a chain of 3+ models that depend on one another
Select them using the above syntax

Relevant log output

No response

Environment

- OS:
- Python:
- dbt:

Which database adapter are you using with dbt?

No response

Additional Context

No response