It says
Error - 5
Unable to process element
Invalid license
The GitHub repository must be licensed under an Open Source Inititative (OSI) approved license. Please include a valid license or alternatively include an OSI approved license as an SPDX identifier (eg. "Apache-2.0") in the license field in the bower.json.
Try to view https://www.webcomponents.org/element/Polymerelements/paper-item/elements/paper-icon-item
It says Error - 5 Unable to process element Invalid license The GitHub repository must be licensed under an Open Source Inititative (OSI) approved license. Please include a valid license or alternatively include an OSI approved license as an SPDX identifier (eg. "Apache-2.0") in the license field in the bower.json.