Changes to be committed:

modified:   pkg/obilua/lua.go
	modified:   pkg/obioptions/version.go

pkg/obilua/lua.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"os"
+	"reflect"
 
 	"git.metabarcoding.org/obitools/obitools4/obitools4/pkg/obiiter"
 	"git.metabarcoding.org/obitools/obitools4/obitools4/pkg/obioptions"
@@ -119,11 +120,17 @@ func LuaWorker(proto *lua.FunctionProto) obiseq.SeqWorker {
 				case *obiseq.BioSequenceSlice:
 					return *val, err
 				default:
-					return nil, fmt.Errorf("worker function doesn't return the correct type %T", val)
+					r := reflect.TypeOf(val)
+					return nil, fmt.Errorf("worker function doesn't return the correct type %s", r)
 				}
 			}
 
-			return nil, fmt.Errorf("worker function doesn't return the correct type")
+			// If worker retuns nothing then it is considered as nil biosequence
+			if _, ok = lreponse.(*lua.LNilType); ok {
+				return nil, nil
+			}
+
+			return nil, fmt.Errorf("worker function doesn't return the correct type %T", lreponse)
 		}
 
 		return f

pkg/obioptions/version.go

@@ -7,7 +7,7 @@ import (
 // TODO: The version number is extracted from git. This induces that the version
 // corresponds to the last commit, and not the one when the file will be
 // commited
-var _Commit = "ad2461a"
+var _Commit = "39dd3e3"
 var _Version = "Release 4.3.0"
 
 // Version returns the version of the obitools package.