xhr-upload: load CompanionClient appropriately

packages/@uppy/xhr-upload/src/index.js

@@ -1,7 +1,7 @@
 const { Plugin } = require('@uppy/core')
 const cuid = require('cuid')
 const Translator = require('@uppy/utils/lib/Translator')
-const { Provider, Socket } = require('@uppy/companion-client')
+const { Provider, RequestClient, Socket } = require('@uppy/companion-client')
 const emitSocketProgress = require('@uppy/utils/lib/emitSocketProgress')
 const getSocketHost = require('@uppy/utils/lib/getSocketHost')
 const settle = require('@uppy/utils/lib/settle')
@@ -311,8 +311,9 @@ module.exports = class XHRUpload extends Plugin {
         fields[name] = file.meta[name]
       })
 
-      const provider = new Provider(this.uppy, file.remote.providerOptions)
-      provider.post(
+      const Client = file.remote.providerOptions.provider ? Provider : RequestClient
+      const client = new Client(this.uppy, file.remote.providerOptions)
+      client.post(
         file.remote.url,
         Object.assign({}, file.remote.body, {
           endpoint: opts.endpoint,