getting error with isPlainObject when using Slate in a Javascript project: TypeError: Object(...) is not a function

[mahuzedada]

I am using slate in a javascript project. When i load the page I get the following error: TypeError: Object(...) is not a function.
The error seems to be thrown in this function:

isText(value) { return isPlainObject(value) && typeof value.text === 'string'; },

Any idea what might be causing this?

[aleksandrenko]

Second that