_createNodeMap() {
    /** @type {Map<number, CpuProfile['nodes'][0]>} */
    const map = new Map();
    for (const node of this._profile.nodes) {
      map.set(node.id, node);
    }

    return map;
  }
Initialization function to enable O(1) access to nodes by node ID.
@return {Map<number, CpuProfile['nodes'][0]>}