$$$ hledger check commodities -f commodities.j
>>>2 /Error: .*commodities.j:6:
  \| 2022-01-01
6 \|     \(a\)             A 1
  \|                     \^\^\^

Strict commodity checking is enabled, and
commodity "A" has not been declared.
Consider adding a commodity directive. Examples:

commodity A1000.00
commodity 1.000,00 A
/
>>>= 1