Unexpected error in "Search in alignment" for short sequences

Scenario:

1. Open "_common_data/scenarios/msa/ma2_gapped.aln".
2. Remove all columns except the first one.
   Expected state: 10 lines with "A" and "T" values
3. Open "Search in Alignment" tab
4. Add multiline: "A" + "T" in the next line
   Expected state: No any errors
   Actual state: Red background and error message: "The value is longer than search region. .."

Note that the search works correctly despite the error message.
Issue is reproducible for "Search in Alignment" and "Search in Sequence" tabs.