SyntaxError: An invalid or illegal string was specified in drawing profile chart

[elcojacobs]

I helped a user debug and stumbled upon this JS error:

SyntaxError: An invalid or illegal string was specified

canvas.fillText(temperature, xCoordinate - 5, yCoordinate);

happens at https://github.com/BrewPi/brewpi-www/blob/master/js/control-panel.js#L281

Profile Name:Exit 148 IPA
Start Date:12/05/2013 19:20:53
Day Temperature Date and Time
0 12/05/2013 19:20:53
1 65 12/06/2013 19:20:53
5 65 12/10/2013 19:20:53
6 68 12/11/2013 19:20:53
7 70 12/12/2013 19:20:53
8 68 12/13/2013 19:20:53
9 65 12/14/2013 19:20:53
13 65 12/18/2013 19:20:53
14 32 12/19/2013 19:20:53

[elcojacobs]

firebug says on breakpoint: temperature: "Nan", yCoordinate: NaN

Happened in firefox, profile chart did not show at all. Refresh button did not work and triggered the error.

Chrome had no trouble displaying the chart.