fix: ignore segments without writer

engine.go

@@ -90,8 +90,8 @@ func (e *engine) renderBlockSegments(block *Block) string {
 	defer e.reset()
 	e.activeBlock = block
 	for _, segment := range block.Segments {
-		props := segment.mapSegmentWithWriter(e.env)
-		if !segment.enabled() {
+		props, err := segment.mapSegmentWithWriter(e.env)
+		if err != nil || !segment.enabled() {
 			continue
 		}
 		e.activeSegment = segment

segment.go

@@ -1,5 +1,7 @@
 package main
 
+import "errors"
+
 //Segment represent a single segment and it's configuration
 type Segment struct {
 	Type            SegmentType              `json:"type"`
@@ -68,7 +70,7 @@ func (segment *Segment) enabled() bool {
 	return segment.writer.enabled()
 }
 
-func (segment *Segment) mapSegmentWithWriter(env environmentInfo) *properties {
+func (segment *Segment) mapSegmentWithWriter(env environmentInfo) (*properties, error) {
 	functions := map[SegmentType]SegmentWriter{
 		Session:   &session{},
 		Path:      &path{},
@@ -92,7 +94,7 @@ func (segment *Segment) mapSegmentWithWriter(env environmentInfo) *properties {
 		}
 		writer.init(props, env)
 		segment.writer = writer
-		return props
+		return props, nil
 	}
-	return nil
+	return nil, errors.New("Unable to map writer")
 }

segment_test.go

@@ -11,7 +11,9 @@ func TestMapSegmentWriterCanMap(t *testing.T) {
 		Type: Session,
 	}
 	env := new(MockedEnvironment)
-	sc.mapSegmentWithWriter(env)
+	props, err := sc.mapSegmentWithWriter(env)
+	assert.NotNil(t, props)
+	assert.NoError(t, err)
 	assert.NotNil(t, sc.writer)
 }
 
@@ -20,6 +22,7 @@ func TestMapSegmentWriterCannotMap(t *testing.T) {
 		Type: "nilwriter",
 	}
 	env := new(MockedEnvironment)
-	sc.mapSegmentWithWriter(env)
-	assert.Nil(t, sc.writer)
+	props, err := sc.mapSegmentWithWriter(env)
+	assert.Nil(t, props)
+	assert.Error(t, err)
 }