Paginator - Uncaught TypeError: this.getOptionLabel(...).toLowerCase is not a function

[ajlai-duetto]

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I'm submitting a ... (check one with "x")

[ x ] bug report
[ ] feature request

Plunkr Case (Bug Reports)
This is actually happening in the demos
https://www.primefaces.org/primereact/#/paginator
and
https://www.primefaces.org/primereact/#/datatable/paginator
Current version is PrimeReact 3.0.0-beta.1 in the demo but it happens on 3.0.0-rc.1 as well

Current behavior
Changing the number of rows per page in paginator and switching browser tabs shows error in console:
Uncaught TypeError: this.getOptionLabel(...).toLowerCase is not a function

Which is happening in

  searchOptionInRange(start, end) {
        for (let i = start; i < end; i++) {
            let opt = this.props.options[i];
            let label = this.getOptionLabel(opt).toLowerCase();
            if (label.startsWith(this.searchValue.toLowerCase())) {
                return opt;
            }
        }

        return null;
    }

Expected behavior
No console error

Minimal reproduction of the problem with instructions
Steps to Reproduce:
1 ) Change the rows per page from 10 to something else in the paginator.
2) Open a new tab in the browser or switch to a different tab and then go back to the tab with the paginator
3) Functionality still works but in the console it shows an error:
Uncaught TypeError: this.getOptionLabel(...).toLowerCase is not a function

Please tell us about your environment:
MacOS

• React version:
  16.6.0

• PrimeReact version:
  3.0.0-rc.1

• Browser:
  Web browser: Chrome Version 71.0.3578.98 (Official Build) (64-bit)

• Language:
  ES6