@juliandeange,
The code that you have shared seems to be working fine. Kindly cross-check the path of the script that you have specified in your app.
1. Save canvasjs.react.js and canvasjs.min.js within source-folder of your React application (src or src/assets or src/lib)
2. Import canvasjs.react.js to your app. (Please specify proper path of script if you have saved it in different folder like src or src/assets or src/lib)
import CanvasJSReact from './canvasjs.react';
Please take a look at this sample project for an working example with proper path.
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Priyanka M S
Team CanvasJS