React version: DevTools version 4.12.2-d14b6a4bdd

Steps To Reproduce

1. Use console.warn from within a React component where the last argument is typeof "symbol"

Link to code example: https://codesandbox.io/s/pedantic-neumann-711ph?file=/src/App.js

The bug only happens when you make a change, so if you use the code sandbox link you need, open a new window, active dev tools, open the React dev tools and then uncomment line 5: // return null only then will the error actually happen.

I've located the culprit to this line of code

https://github.com/facebook/react/blob/0e100ed00fb52cfd107db1d1081ef18fe4b9167f/packages/react-devtools-shared/src/backend/console.js#L146-L147

And would offer the following change

const alreadyHasComponentStack = typeof lastArg === "string" && isStringComponentStack(lastArg);

The current behavior

React DevTools is implicitly converting a Symbol to a string.

The expected behavior

React DevTools does not implicitly try to convert a Symbol to a string.