Avoid error if borderOpts.dash is undefined

[HieroglypH]

As the title suggests.

In my case,
I was implementing a radar chart and had set options.scales.r.border.dash to [3,3],
In certain environments, an error would occur and the chart would not display.

The error message is

Failed to execute 'setLineDash' on 'CanvasRenderingContext2D': The provided value cannot be converted to a sequence.

Reproduction rate is not 100%.
About 80% are displayed correctly with no errors.

I was never able to pinpoint the cause, but for some reason,
options.scales.r.border.dash seemed to become undefined internally.
Therefore, an error occurred in setLineDash in function drawRadiusLine and the process stopped.

At the very least, I tried to modify it so that the process would not stop due to an error.