Google Chart not displaying

[Steven Davison]

Hi, 

I'm trying to get a chart to display based on values from a mysql db. I've managed to output the data into a json array, but the chart will not show when this is used. 

https://pastebin.com/LW19H8nN 

My code is above. In this view, the data has been 'echoed' out of php. (line 26) it has not been hard coded. 

What would be causing the chart not to render? Is there a way of forcing google charts to show errors?

Many thanks,

Steve