What does the error message "Cannot read property 'pick' of null" mean in relation to DocumentPicker?

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The error message "Cannot read property 'pick' of null" means that the code is trying to access the 'pick' property of an object that is null (i.e. it does not exist). In relation to DocumentPicker, it could mean that the file picker component is not properly initialized or the document picker component is not installed in the application.