typescript: `readonly` results in syntax error

**Describe the bug**
`type PassA = readonly T[];` will not be displayed in the output.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to https://astexplorer.net/#/gist/bea26d669eb5836fa3cfcc82692f568b/847a7a4b88865ea95b0ab6b9b8c2eaafb10f556c

3. Scroll down to output window
4. See error

**Expected behavior**
No syntax error as in https://www.typescriptlang.org/play?#code/C4TwDgpgBAKlC8UCuA7A1ig9gdxQbgChRIoBZJYAQwCMAbCAQQCcnKQAeGAPgSmdY7dCRcNAAKlAM6SGvJhEoATTClohYAbQC6hYuKmSAQr3JU6jFm05ddoqBOkBhXgCUFy1SH5WhBESQAxSgBLWllEGG1bQJDaY0RvQRsgA

**Screenshots**

**Browser (please complete the following information):**
- OS: Ubuntu 20.04
- Browser chrome
- Version 79

**astexplorer settings:**
- Selected parser: `@typescript-eslint/parser`
- Selected transformer (if applicable): [e.g. jscodeshift]
- Contents of the local storage key `explorerSettingsV1` (code can be removed if you don't want it to be public)

**Additional context**
N/A