How to use the scratch-blocks.inject function in scratch-blocks

setBlocks (blocksRef) {
        if (!blocksRef) return;
        this.blocks = blocksRef;
        const workspaceConfig = defaultsDeep({},
            CustomProcedures.defaultOptions,
            this.props.options
        );

        // @todo This is a hack to make there be no toolbox.
        const oldDefaultToolbox = ScratchBlocks.Blocks.defaultToolbox;
        ScratchBlocks.Blocks.defaultToolbox = null;
        this.workspace = ScratchBlocks.inject(this.blocks, workspaceConfig);
        ScratchBlocks.Blocks.defaultToolbox = oldDefaultToolbox;

        // Create the procedure declaration block for editing the mutation.
        this.mutationRoot = this.workspace.newBlock('procedures_declaration');
        // Make the declaration immovable, undeletable and have no context menu
        this.mutationRoot.setMovable(false);
        this.mutationRoot.setDeletable(false);
        this.mutationRoot.contextMenu = false;

        this.workspace.addChangeListener(() => {
            this.mutationRoot.onChangeFn();
            // Keep the block centered on the workspace
            const metrics = this.workspace.getMetrics();
            const {x, y} = this.mutationRoot.getRelativeToSurfaceXY();
            const dy = (metrics.viewHeight / 2) - (this.mutationRoot.height / 2) - y;
            let dx = (metrics.viewWidth / 2) - (this.mutationRoot.width / 2) - x;