Gatsby: Typescript 3.8: Fail to build site with type-only import/export

[tom-sherman]

Description

I cannot use Typescript 3.8 with type-only imports and exports

Steps to reproduce

In one file export a type

// some-file.ts
export type Foo = 'bar'

In another file, import that type using the new type-only import/export syntax

import type { Foo } from './some-file'

Expected result

Gatsby should build the site

Actual result

There is an "unexpected token" error.

 ERROR #98123  WEBPACK

Generating SSR bundle failed

Environment

I'm using WSL with Fish shell but we're also getting the issue in CI which is pure Ubuntu 18.

  System:
    OS: Linux 4.19 Ubuntu 16.04.4 LTS (Xenial Xerus)
    CPU: (4) x64 Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz
    Shell: 4.3.48 - /bin/bash
  Binaries:
    Node: 12.13.1 - ~/.config/nvm/12.13.1/bin/node
    Yarn: 1.22.4 - /usr/bin/yarn
    npm: 6.12.1 - ~/.config/nvm/12.13.1/bin/npm
  Languages:
    Python: 2.7.12 - /usr/bin/python
  npmPackages:
    gatsby: 2.20.3 => 2.20.3
    gatsby-plugin-alias-imports: 1.0.5 => 1.0.5
    gatsby-plugin-mdx: 1.1.1 => 1.1.1
    gatsby-plugin-react-helmet: 3.2.1 => 3.2.1
    gatsby-plugin-treat: 1.2.3 => 1.2.3
    gatsby-plugin-typescript: 2.3.1 => 2.3.1
    gatsby-remark-prismjs: 3.4.1 => 3.4.1
    gatsby-source-filesystem: 2.2.2 => 2.2.2

[tom-sherman]

This feature is supported Babel in v7.9.0 which looks to be the version that is installed by gatsby-plugin-typescript so I'm not sure why this isn't working.

> npm ls @babel/preset-typescript

└─┬ [email protected]
  └── @babel/[email protected]

> npm ls @babel/core

└─┬ [email protected]
  └── @babel/[email protected] 

[tiagovtristao]

Hi @tom-sherman,

I was facing the same issue but was able to fix it using the following steps (using yarn in my project):

1. Delete yarn.lock
2. yarn add @babel/core

It seems the yarn.lock contents were pointing @babel/core to <7.9, and this was also causing certain upgraded babel packages to complain about the missing @babel/core@^7.9 peer dependency.

Hope this works for you as well.

[danabrit]

@tom-sherman Can you please confirm whether @tiagovtristao 's solution resolved your issue?

[freiksenet]

Hello!

I'll be closing this issue as there has been no activity for 2 months.

Thank you for using Gatsby! purple_heart