chartjs-plugin-labels.js:433 Uncaught TypeError: Cannot read property 'register' of undefined at chartjs-plugin-labels.js:433
/*official chartjs-plugin-labels does not currently work with most
recent version of chart.js and does not appear to be maintained,
this guys github fork seems to work alright though */
https://github.com/DavideViolante/chartjs-plugin-labels
Update: There is an offical labels from chartjs that you should instead:
https://github.com/chartjs/chartjs-plugin-datalabels