bug: Unexpected character '#' on build

Describe the bug

Bundling via webpack (via netlify-lambda) fails with the following error:

ERROR in ../node_modules/@panva/jose/lib/jws/sign.js 14:2
Module parse failed: Unexpected character '#' (14:2)

(Detailed stack trace at the end of this post.)

It appears that webpack barfs at this kind of syntax with the #

class Sign {
  #b64
  #payload
  #recipients
  ...

I’m submitting an issue here because ‘#’ appears to be invalid syntax.

To Reproduce

Steps to reproduce the behaviour:

1. git clone https://github.com/rendall/jwt-implementation/tree/%40panva/jose
2. cd ./jwt* or otherwise into project directory
3. npm / yarn install
4. npm / yarn run build

Expected behaviour

That there be no Unexpected character error.

Environment:

• @panva/jose version: 1.0.0
• node version: v12.0.0

Additional context Add any other context about the problem here.

• the bug is happening on latest @panva/jose too.
• i have tried DEBUG (see readme.md) and can see the issue is with the provider and not my code.
• i have searched the issues tracker on github for similar issues and couldn’t find anything related.

Detailed Error stack trace

netlify-lambda: Building functions
Hash: c3ac99528bc9843d63e5
Version: webpack 4.30.0
Time: 2110ms
Built at: 04/27/2019 7:55:37 AM
  Asset     Size  Chunks  Chunk Names
auth.js  124 KiB       0  auth
Entrypoint auth = auth.js
 [0] external "crypto" 42 bytes {0} [built]
 [2] ../node_modules/@panva/jose/lib/errors.js 275 bytes {0} [built] [failed] [1 error]
 [5] ../node_modules/@panva/jose/lib/jwk/key/base.js 5.89 KiB {0} [built]
[10] ../node_modules/@panva/jose/lib/jwks/keystore.js 202 bytes {0} [built] [failed] [1 error]
[16] ../node_modules/@panva/jose/lib/jwk/generate.js 1.5 KiB {0} [built]
[18] ../node_modules/@panva/jose/lib/jws/index.js 525 bytes {0} [built]
[31] ../node_modules/@panva/jose/lib/jwk/index.js 298 bytes {0} [built]
[37] ../node_modules/@panva/jose/lib/index.js 178 bytes {0} [built]
[38] ../node_modules/dotenv/lib/main.js 2.87 KiB {0} [built]
[39] ./auth.js 3.21 KiB {0} [built]
[40] ../node_modules/@panva/jose/lib/jwe/index.js 570 bytes {0} [built]
[85] ../node_modules/@panva/jose/lib/jwks/index.js 70 bytes {0} [built]
[89] ../node_modules/@panva/jose/lib/jwt/index.js 150 bytes {0} [built]
[92] external "fs" 42 bytes {0} [built]
[93] external "path" 42 bytes {0} [built]
    + 79 hidden modules

ERROR in ../node_modules/@panva/jose/lib/jws/sign.js 14:2
Module parse failed: Unexpected character '#' (14:2)
You may need an appropriate loader to handle this file type.
|
| class Sign {
>   #b64
|   #payload
|   #recipients
 @ ../node_modules/@panva/jose/lib/jws/index.js 1:13-30
 @ ../node_modules/@panva/jose/lib/index.js
 @ ./auth.js

[panva]

Then don’t transpile @panva/jose dependency until your tooling is ready to recognize the new javascript syntax.

[panva]

I’ve made @panva/jose compatible with lts/dubnium, it is now being tested with Node.js ^10.13.0 || >=12.0.0 and Electron ^6.0.0

It is not without caveats, but they are acceptable.

• Importing X.509 certificates and handling x5c is only supported when Node.js >= 12.0.0 runtime is detected
• OKP keys are only supported when Node.js >= 12.0.0 runtime is detected