Latest webpack update breaks this plugin

[ehuelsmann]

The latest webpack upgrade seems to break this plugin (see ledgersmb/LedgerSMB#9769). The backtrace suggests a problem in the plugin:

ERROR in ./bootstrap.js
Module parse failed: Cannot use 'in' operator to search for 'start' in undefined
File was parsed as module type 'javascript/auto'.
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
TypeError: Cannot use 'in' operator to search for 'start' in undefined
    at set loc (/srv/ledgersmb/UI/node_modules/webpack/lib/Dependency.js:195:15)
    at DojoAMDDefineDependencyParserPlugin.processItem (/srv/ledgersmb/UI/node_modules/dojo-webpack-plugin/lib/DojoAMDDependencyParserMixin.js:112:12)
    at /srv/ledgersmb/UI/node_modules/dojo-webpack-plugin/lib/DojoAMDDependencyParserMixin.js:38:10
    at Array.forEach (<anonymous>)
    at DojoAMDDefineDependencyParserPlugin.processArray (/srv/ledgersmb/UI/node_modules/dojo-webpack-plugin/lib/DojoAMDDependencyParserMixin.js:32:16)
    at DojoAMDDefineDependencyParserPlugin.processCallDefine (/srv/ledgersmb/UI/node_modules/webpack/lib/dependencies/AMDDefineDependencyParserPlugin.js:374:24)
    at DojoAMDDefineDependencyParserPlugin.processCallDefine (/srv/ledgersmb/UI/node_modules/dojo-webpack-plugin/lib/DojoAMDDefineDependencyParserPlugin.js:47:20)
    at Hook.eval [as call] (eval at create (/srv/ledgersmb/UI/node_modules/tapable/lib/HookCodeFactory.js:19:10), <anonymous>:7:16)
    at Hook.CALL_DELEGATE [as _call] (/srv/ledgersmb/UI/node_modules/tapable/lib/Hook.js:16:14)
    at JavascriptParser._callHooksForInfo (/srv/ledgersmb/UI/node_modules/webpack/lib/javascript/JavascriptParser.js:4766:24)

webpack compiled with 1 error

The content of ./bootstrap.js is generated as:

    // Compile bootstrap module as a virtual one
    const VirtualModulesPluginOptions = {
        "./bootstrap.js":
            `/* eslint-disable */\n` +
            `define(["dojo/parser","dojo/ready"` +
//            includedRequires.join('","') +
            `], function(parser, ready) {\n` +
            `    ready(function() {\n` +
            `    });\n` +
            `    return {};\n` +
            `});`
    };