MImageBody doesn't check whether it is still mounted before setState

[JaniM]

Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check the code for the MImageBody component

Happens in componentDidMount's promse.

            thumbnailPromise.then((thumbnailUrl) => {
                return decryptFile(content.file).then(function(blob) {
                    decryptedBlob = blob;
                    return readBlobAsDataUri(blob);
                }).then((contentUrl) => {
                    this.setState({ // <----
                        decryptedUrl: contentUrl,
                        decryptedThumbnailUrl: thumbnailUrl,
                        decryptedBlob: decryptedBlob,
                    });
                    this.props.onWidgetLoad();
                });
            }).catch((err) => {
                console.warn("Unable to decrypt attachment: ", err);
                // Set a placeholder image when we can't decrypt the image.
                this.setState({
                    error: err,
                });
            }).done();