`DataFrame.apply` passes empty row to callback when the cell has objects as values

[applegrew]

Describe the bug
DataFrame.apply removes all values of type object. It seems to accept only string or numbers.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://codesandbox.io/s/summer-forest-xzq2rq?file=/src/index.js
2. Open the console.

Expected behavior
The callback should be called with non-zero length array.

Danfojs version:

• 1.1.1 (browser)

Additional context
This happens since apply internally removes all values which are "empty". However, the "empty" logic is weird (

danfojs/src/danfojs-base/shared/utils.ts

Line 94 in bdf0a24

return value === undefined || value === null || (isNaN(value as any) && typeof value !== "string");

) and it removes all values if they are not string or number. In my case I have JS objects which internally have data.

[risenW]

1. https://codesandbox.io/s/summer-forest-xzq2rq?file=/src/index.js

The issue is not the apply function, The problem is that you're creating a DataFrame from nested objects, which is not supported atm.