fx: Treat empty nodes as zero values

decode_test.go

@@ -591,6 +591,10 @@ func TestDecoder(t *testing.T) {
 			"v:\n - A\n - B",
 			map[string]interface{}{"v": []interface{}{"A", "B"}},
 		},
+		{
+			"v:\n-",
+			map[string][]string{"v": []string{""}},
+		},
 		{
 			"v:\n - A\n - B\n - C",
 			map[string][]string{"v": []string{"A", "B", "C"}},

parser/parser.go

@@ -327,20 +327,23 @@ func (p *parser) parseSequenceEntry(ctx *context) (*ast.SequenceNode, error) {
 	for tk.Type == token.SequenceEntryType {
 		ctx.progress(1) // skip sequence token
 		tk = ctx.currentToken()
-		if tk == nil {
-			return nil, errors.ErrSyntax("empty sequence entry", ctx.previousToken())
-		}
 		var comment *ast.CommentGroupNode
-		if tk.Type == token.CommentType {
-			comment = p.parseCommentOnly(ctx)
-			tk = ctx.currentToken()
-			if tk.Type == token.SequenceEntryType {
-				ctx.progress(1) // skip sequence token
+		var value ast.Node
+		var err error
+		if tk == nil {
+			value = &ast.NullNode{}
+		} else {
+			if tk.Type == token.CommentType {
+				comment = p.parseCommentOnly(ctx)
+				tk = ctx.currentToken()
+				if tk.Type == token.SequenceEntryType {
+					ctx.progress(1) // skip sequence token
+				}
+			}
+			value, err = p.parseToken(ctx.withIndex(uint(len(sequenceNode.Values))), ctx.currentToken())
+			if err != nil {
+				return nil, errors.Wrapf(err, "failed to parse sequence")
 			}
-		}
-		value, err := p.parseToken(ctx.withIndex(uint(len(sequenceNode.Values))), ctx.currentToken())
-		if err != nil {
-			return nil, errors.Wrapf(err, "failed to parse sequence")
 		}
 		if comment != nil {
 			comment.SetPath(ctx.withIndex(uint(len(sequenceNode.Values))).path)

parser/parser_test.go

@@ -679,19 +679,6 @@ a
 [1:1] unterminated flow mapping
 >  1 | { "key": "value"
        ^
-`,
-		},
-		{
-			`
-a:
-- b: c
-- `,
-			`
-[4:1] empty sequence entry
-   2 | a:
-   3 | - b: c
->  4 | -
-       ^
 `,
 		},
 	}