TypeError: The “original” argument must be of type Function in Vue.js application

I’m trying to call a soap webservice using the ‘soap’ module in my Vue SPA, but I get this error just by importing the module. I already searched a lot but didn’t find a solution.

My code:

// /src/services/soapService.js
import soap from 'soap';

var soapService = {

    users: {
        getAllUsers() {
            const url = 'http://127.0.0.2:8000/?wsdl'

            soap.createClient(url, function(err, client) {
                client.getAllUsers(function(err, result) {
                    console.log(result);
                })
            })
        }
    }
}

export default soapService;

Then I call my function in a Vue component:

<template>
  <div></div>
</template>

<script>
import soapApi from '@/services/soapService'

export default {
  name: 'Users',

  methods: {
    getAllUsers() {
      this.allUsers = soapApi.users.getAllUsers();
    }
  },

  mounted() {
    this.getAllUsers();
  }

}
</script>

When I try to load the Users.vue component, I get this error:

TypeError: The "original" argument must be of type Function
    at promisify (util.js?3022:602)
    at eval (index.js?4f62:7)
    at Object.../node_modules/get-stream/index.js (0.js:529)
    at __webpack_require__ (app.js:854)
    at fn (app.js:151)
    at eval (client.js?e3c8:24)
    at Object.../node_modules/soap/lib/client.js (0.js:586)
    at __webpack_require__ (app.js:854)
    at fn (app.js:151)
    at Object.eval (soap.js?3fc0:19)
abort @ vue-router.esm.js?8c4f:2316
eval @ vue-router.esm.js?8c4f:2369
eval @ vue-router.esm.js?8c4f:2138
eval @ vue-router.esm.js?8c4f:2203
Promise.then (async)
eval @ vue-router.esm.js?8c4f:2150
eval @ vue-router.esm.js?8c4f:2171
eval @ vue-router.esm.js?8c4f:2171
flatMapComponents @ vue-router.esm.js?8c4f:2170
eval @ vue-router.esm.js?8c4f:2106
iterator @ vue-router.esm.js?8c4f:2362
step @ vue-router.esm.js?8c4f:2004
step @ vue-router.esm.js?8c4f:2008
step @ vue-router.esm.js?8c4f:2008
step @ vue-router.esm.js?8c4f:2008
runQueue @ vue-router.esm.js?8c4f:2012
confirmTransition @ vue-router.esm.js?8c4f:2392
transitionTo @ vue-router.esm.js?8c4f:2260
push @ vue-router.esm.js?8c4f:2715
push @ vue-router.esm.js?8c4f:3037
handler @ vue-router.esm.js?8c4f:1139
invokeWithErrorHandling @ vue.runtime.esm.js?2b0e:1863
invoker @ vue.runtime.esm.js?2b0e:2188
original._wrapper @ vue.runtime.esm.js?2b0e:6961

Node v16.11.1
npm v8.1.3
vue v2.6.11