Do you want to request a feature or report a bug?
This is a bug, either with our example files or with Draft.js itself.
What is the current behavior?
On master if you run the 'universal' example under examples/draft-0-9-1/ and try typing into the editor, the editor does not update and errors are thrown in the console:

Similarly if you run the 'tex' example under examples/draft-0-9-1/ and try typing into the editor, various errors are thrown and things can quickly get into an invalid state, where wrong characters and selection state are created:

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. You can use this jsfiddle to get started: https://jsfiddle.net/stopachka/m6z0xn4r/.
cd examples/draft-0-9-1/tex && yarn install && yarn start then visit localhost:3000 and try editing the 'tex' examples and the text.
cd examples/draft-0-9-1/universal && yarn install && yarn build && yarn start then visit localhost:3003 and try typing text.
NOTE: The problem is only present in the 0.9.1 examples, not the 0.10.1 examples.
What is the expected behavior?
Entering text should update the editor as normal, not throw errors.
Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?
Tested with the master branch in Firefox.