React app error: Missing credentials in config

I am building a React.js app in which I display some data hosted on AWS DynamoDB. I wrote a module called getList.js which makes a request to AWS DynamoDB to get the data. When I test this module using "node getList.js" it returns the expected data, no problem. [Should note, I have stored my AWS credentials as recommended in .aws/credentials] Here is the code for my getList.js module:

var AWS = require("aws-sdk");
AWS.config.region = region;


module.exports = getList;

function getList (callback) {
    const documentClient = new AWS.DynamoDB.DocumentClient();

    var params = {
        TableName: "tableName"
    };

    
    documentClient.scan(params, function(err, data) {
        if (err) {
            console.log("ERROR", err)        
        } 
        else {
            //get data, etc, return in callback
            callback(data);
        }
    });
}

Now I am trying to call this module in my React app, as shown below:

import React, { Component } from 'react';
import './App.css';
let listProject = require('../../modules/getList')

class App extends Component {
  state = {
    list: []
  }

  componentDidMount = () => {
    listProject(function(res) {
      this.setState({ list: res})
    });      
  }

  render() {
    return (
      <div className="App">
        <div className="App-header">
          <h2>Automaticity</h2>
        </div>
        <p className="App-intro">
          {JSON.stringify(this.state.list)}
        </p>
      </div>
    );
  }
}

export default App;

However, when I start the React app in my browser, the app loads fine, but the data is never retrieved, and I get this error:

Error: Missing credentials in config (specifically the error occurs when getList.js calls documentClient.scan(params, function(err, data)

Am I missing some dependency or code that will make my setup work??

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