Why am I getting undefined is not an object (evaluating 'ReactPropTypes.string') error?

Here's the thing, I'm dealing with like 10 .js files so posting them here would be way too much. My question is, what are the possible reasons I'm getting this error? I understand it's somewhat of a vague question, but I can't find an answer anywhere to this.

On top of this, there are absolutely no errors in any of these .js files. It's only when I hit Run to see the result of my code in the simulator do I see the error (pic below).

My apologies again if it's too vague, I just don't know where else to turn.

Could it be in this file? I think it's all correct here. I just have a slight feeling this file is the problem.

Here's Router.js

import React, { Component } from 'react';
import { Navigator } from 'react-native';
import Home from './Home';
import Location from './Location';
import Interest from './Interest';
import Login from './Login';
import Signup from './Signup';

export default class Router extends Component {
  constructor() {
    super();
  }

  configureScene(route, routeStack) {
    return Navigator.SceneConfigs.FloatFromBottomAndroid;
  }

renderScene(route, navigator) {
  if (route.name === 'Home') {
    return (
      <Home
      navigator={navigator}
      {...route.passProps}
      />
    );
  }
  if (route.name === 'Location') {
    return (
      <Location
      navigator={navigator}
      {...route.passProps}
      />
    );
  }
  if (route.name === 'Interest') {
    return (
      <Interest
      navigator={navigator}
      {...route.passProps}
      />
    );
  }
  if (route.name === 'Login') {
    return <Login navigator={navigator} {...route.passProps} />
  }
  if (route.name == 'Signup') {
      return ( <Signup navigator={navigator} {...route.passProps} /> )
    }
}

render() {
  return (
    <Navigator
      configureScene={this.configureScene}
      initialRoute={{ name: 'Home', title: 'Home' }}
      renderScene={this.renderScene}
    />
  );
}

}

Weird error