"TypeError: Cannot read property 'apply' of undefined" when handlebars version > 4.6.0

[ivakarlec]

After the release of handlebars@4.6.0 (2nd week of January 2020) I get a "TypeError: Cannot read property 'apply' of undefined":
{code}
TypeError: Cannot read property 'apply' of undefined
at Object.wrapper (/myProject/node_modules/handlebars/lib/handlebars/internal/wrapHelper.js:5:19)
at Object.eval (eval at createFunctionContext (/myProject/node_modules/handlebars/lib/handlebars/compiler/javascript-compiler.js:260:23), :13:196)
at main (/myProject/node_modules/handlebars/lib/handlebars/runtime.js:230:22)
at ret (/myProject/node_modules/handlebars/lib/handlebars/runtime.js:250:12)
at ret (/myProject/node_modules/handlebars/lib/handlebars/compiler/compiler.js:548:21)
at Object.invokePartial (/myProject/node_modules/handlebars/lib/handlebars/runtime.js:405:12)
at Object.invokePartialWrapper [as invokePartial] (/myProject/node_modules/handlebars/lib/handlebars/runtime.js:82:39)
at Object.eval (eval at createFunctionContext (/myProject/node_modules/handlebars/lib/handlebars/compiler/javascript-compiler.js:260:23), :15:28)
at main (/myProject/node_modules/handlebars/lib/handlebars/runtime.js:230:22)
at ret (/myProject/node_modules/handlebars/lib/handlebars/runtime.js:250:12)
at ret (/myProject/node_modules/handlebars/lib/handlebars/compiler/compiler.js:548:21)
at ExpressHandlebars._renderTemplate (/myProject/node_modules/express-handlebars/lib/express-handlebars.js:250:12)
at ExpressHandlebars. (/myProject/node_modules/express-handlebars/lib/express-handlebars.js:173:21)
{code}
There are some breaking changes in the handlebars@4.6.0 release: 770d746

[ivakarlec]

Sorry, it's more likely an issue for express-handlebars...

[nknapp]

Please add details.

The function in your stack trace is new. It may be a problem here.

[nknapp]

This issue should be fixed in Handlebars 4.7.2.

[MatYRiCs]

This issue should be fixed in Handlebars 4.7.2.

It dosen't work for me with v. 4.7.2.

This is my helper file

module.exports = {
    truncate: function (str, num) {
        if (str.length <= num) {
            return str
        }
        return str.slice(0, num) + '...'
    }
};

And adding this to my app.js file:

const truncate = require('./helpers/hbs')

const hbs = exphbs.create({
    helpers: truncate
});

And this is how I use the function in my handlebars file:

            <tbody>
                {{#each systems}}
                <tr>
                    <td class="text-center">{{#each this}} {{ truncate name 10 }} {{/each}} </td>
                    <td class="text-center">{{#each this}} {{table}} {{/each}}</td>
                    <td class="text-center">
                        <button type="button" class="ikon ikon-rundt ikon-rediger" title="Rediger"></button>
                        <button type="button" class="ikon ikon-rundt ikon-slet" title="Slet"></button>
                    </td>
                </tr
...

I keep getting:
TypeError: Cannot read property 'length' of undefined

[nknapp]

It's a different problem (differen error message). Please have a look if it is related to #1642
Otherwise open a new issue, please also provide the template-input there (i.e. the parameter to "res.render(...")