The root of the problem is that search always tries to do a full text search. It should not if the keyword is blank.
Npgsql.NpgsqlException:
syntax error in tsquery: "''"
Severity: ERROR
Code: 42601
at Npgsql.NpgsqlState+<ProcessBackendResponses>d__0.MoveNext () [0x00000] in <filename unknown>:0
at Npgsql.ForwardsOnlyDataReader.GetNextResponseObject (Boolean cleanup) [0x00000] in <filename unknown>:0
The root of the problem is that search always tries to do a full text search. It should not if the keyword is blank.