comark/charts/missing-x · Fill in every row's x value

A row without an x value has nowhere to go on the chart, so it's left out. Fill it in, or remove the row.

Incorrect

::chart{title="Ducks per pond"}
| pond | ducks |
| --- | --: |
| north | 12 |
|  | 7 |
| east | 9 |
::

lint-comark example.mdexample.md:1:1 comark/charts/missing-x::chart 1: row 2 has no pond.Fill it in, or remove the row.✖ 1 problem

Correct

::chart{title="Ducks per pond"}
| pond | ducks |
| --- | --: |
| north | 12 |
| south | 7 |
| east | 9 |
::

lint-comark example.md✔ No problems