exit with non-zero status on empty input

internal/engine/engine_test.go

@@ -104,6 +104,33 @@ func TestStart_FastPath_InvalidJSON(t *testing.T) {
 	assert.Len(t, errs, 1, "Expected one error message")
 }
 
+func TestStart_EmptyInput(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+	}{
+		{"empty", ""},
+		{"whitespace", "   "},
+		{"newlines", "\n\t\n"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			parser := jsonx.NewJsonParser(strings.NewReader(tc.input), false)
+
+			var errs []string
+			opts := engine.Options{
+				WriteOut: func(s string) {},
+				WriteErr: func(s string) { errs = append(errs, s) },
+			}
+			exitCode := engine.Start(parser, []string{"."}, opts)
+
+			assert.Equal(t, 1, exitCode)
+			assert.Len(t, errs, 1)
+		})
+	}
+}
+
 func TestStart_EscapeSequences(t *testing.T) {
 	input := `{"emoji": "\ud83d\ude80"}`
 	parser := jsonx.NewJsonParser(strings.NewReader(input), false)

internal/jsonx/json.go

@@ -52,10 +52,11 @@ func (p *JsonParser) Parse() (node *Node, err error) {
 			err = p.errorSnippet(fmt.Sprintf("%v", r))
 		}
 	}()
-	if p.count > 0 {
-		p.skipWhitespace()
-	}
+	p.skipWhitespace()
 	if p.eof {
+		if p.count == 0 {
+			return nil, fmt.Errorf("empty input")
+		}
 		return nil, io.EOF
 	}
 	node = p.parseValue(true)
@@ -79,7 +80,7 @@ func (p *JsonParser) Recover() *Node {
 	}
 
 	end := p.end - 1
-	if p.data[end-1] == '\n' {
+	if end > 0 && p.data[end-1] == '\n' {
 		end-- // Trim trailing newline.
 	}
 

internal/jsonx/jsonx_test.go

@@ -56,6 +56,9 @@ func TestJsonParser_Parse_error(t *testing.T) {
 	tests := []struct {
 		input string
 	}{
+		{``},
+		{`   `},
+		{"\n\t\n"},
 		{`"abc`},
 		{`truth`},
 		{`1e`},