bug: Can't sign or encrypt on Node v11.14.0

[niekvb]

Describe the bug
This package does not work properly on Node v11.14.0. Using the JWT.sign() and/or JWE.encrypt() method(s) result in the following exception:

TypeError: keyObject.asInput is not a function
    at sign (/node_modules/@panva/jose/lib/jwa/rsassa_pss.js:25:27)
    at sign (/node_modules/@panva/jose/lib/jwa/index.js:58:29)
    at Sign.[PROCESS_RECIPIENT] (/node_modules/@panva/jose/lib/jws/sign.js:108:50)
    at Array.forEach (<anonymous>)
    at Sign.sign (/node_modules/@panva/jose/lib/jws/sign.js:126:24)
    at single (/node_modules/@panva/jose/lib/jws/index.js:7:14)
    at Object.module.exports [as sign] (/node_modules/@panva/jose/lib/jwt/sign.js:77:14)
    at Object.<anonymous> (/dist/modules/authorize/index.js:12:24)
    at Module._compile (internal/modules/cjs/loader.js:816:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:827:10)
    at Module.load (internal/modules/cjs/loader.js:685:32)
    at Function.Module._load (internal/modules/cjs/loader.js:620:12)
    at Module.require (internal/modules/cjs/loader.js:723:19)
    at require (internal/modules/cjs/helpers.js:14:16)
    at Object.<anonymous> (/dist/server.js:8:21)
    at Module._compile (internal/modules/cjs/loader.js:816:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:827:10)
    at Module.load (internal/modules/cjs/loader.js:685:32)
    at Function.Module._load (internal/modules/cjs/loader.js:620:12)
    at Function.Module.runMain (internal/modules/cjs/loader.js:877:12)
    at internal/main/run_main_module.js:21:11

To Reproduce

Steps to reproduce the behaviour:

const jose = require('@panva/jose');

const jwk = jose.JWK.generate("RSA");
const jwt = jose.JWT.sign({ abc: 123 }, jwk);
const jwe = jose.JWE.encrypt(jwt, jwk);

Expected behaviour
Proper signing and encryption of the token.

Environment:

• @panva/jose version: 1.9.1
• node version: v11.14.0

Additional context
The README file states that Node >= v12.0.0 is recommended, so this might be a wontfix. BUT the information in this issue might be useful to others.

• the bug is happening on latest @panva/jose too.
• i have searched the issues tracker on github for similar issues and couldn't find anything related.

[panva]

The supported runtime is ^10.13.0 || >=12.0.0

11.x is not something i will be figuring out backports for since it has reached its end of life in June