where: more convenience handling nothing

Basics

• I have done a basic search through the issue tracker to find similar or related issues.
• I have made myself familiar with the available features of Nushell for the particular area this enhancement request touches.

Related problem

I have trouble filtering a list based on a column that can be absent.

The most naive approach fails when the column is absent:

❯ [{a:[1] b:2} {b:2}] | where {|r| $r.a | where $it == 1 | is-not-empty }
Error: nu::shell::column_not_found

  × Cannot find column 'a'
   ╭─[repl_entry #16:1:34]
 1 │ [{a:[1] b:2} {b:2}] | where {|r| $r.a | where $it == 1 | is-not-empty }
   ·                                  ─┬ ┬
   ·                                   │ ╰── column 'a' is missing in one or more values
   ·                                   ╰── value originates here
   ╰────
  help: If some rows have this column, try using 'a?' for optional access, or pre-fill using the `default` command

Following the advice to add the question mark operator ? does not really help, because now where complains that nothing is not a list:

❯ [{a:[1] b:2} {b:2}] | where {|r| $r.a? | where $it == 1 | is-not-empty }
Error: nu::shell::only_supports_this_input_type

  × Input type not supported.
   ╭─[repl_entry #15:1:37]
 1 │ [{a:[1] b:2} {b:2}] | where {|r| $r.a? | where $it == 1 | is-not-empty }
   ·                                     ┬    ──┬──
   ·                                     │      ╰── only list<any>, table, and range input data is supported
   ·                                     ╰── input type: nothing
   ╰────

When also adding default from the first suggestion, it finally works:

❯ [{a:[1] b:2} {b:2}] | where {|r| $r.a? | default [] | where $it == 1 | is-not-empty }
 #      a      b
 0    0   1    2

However:

1. This is inconvenient and bulky, particularly assuming interactive use of nushell.
2. If one starts at the 2nd form, there is no helpful recommendation.
3. The recommendation on the first form is "or pre-fill", but I believe it should have been "and pre-fill", because ? alone does not solve the problem.

Describe the solution you'd like

• I would expect where (and any other command taking list as input) to also be able to handle nothing and treat it as the empty list [].
• I would expect where (and others), when nothing as an unsupported input type is passed (in case this cannot be treated as the empty list), to recommend to use default.
• The recommendation for nu::shell::column_not_found should probably recommend the use of both ? and default, not just either one of them.

Describe alternatives you've considered

No response

Additional context and details