I quick tested timechart command and found negative span value is not allowed in our grammar. But zero-span validation is missing. Let me create an issue and raise separate PR to fix.

opensearchsql> source=test_data_2023 | timechart span=0m per_second(packets);
TransportError(500, 'SearchPhaseExecutionException', {'error': 
{'reason':'Error occurred in OpenSearch engine: all shards failed', 'details': 'Shard[0]:
  java.lang.IllegalArgumentException: Zero or negative time interval not supported\n\n
    For more details, please send request for Json format to see the raw response from OpenSearch engine.',
      'type': 'SearchPhaseExecutionException'}, 'status': 400})

opensearchsql> source=test_data_2023 | timechart span=-1m per_second(packets);
{'reason': 'Invalid Query', 'details': "[-] is not a valid term at this part of the query: '...23
  | timechart span=-' <-- HERE. extraneous input '-' expecting {SPANLENGTH, INTEGER_LITERAL}",
    'type': 'SyntaxCheckException'}

Originally posted by @dai-chen in #4464 (comment)