Dashboard: Missing error handling for cancelling a run

[AlanGreene]

We're missing error handling for cancelling a run :see_no_evil:

https://github.com/tektoncd/dashboard/blob/266f8030f92a3d321ba648b1d97512f8c2280dfe/src/containers/PipelineRuns/PipelineRuns.js#L115

_Originally posted by @steveodonovan in https://github.com/tektoncd/dashboard/pull/1877#discussion_r552587809_

[kobaji]

Hi @AlanGreene and all,
I thought I should implement it in the same way as the following part, but is it correct?

https://github.com/tektoncd/dashboard/blob/266f8030f92a3d321ba648b1d97512f8c2280dfe/src/containers/PipelineRuns/PipelineRuns.js#L127-L139

If so, our team would try this issue.

[AlanGreene]

@kobaji yes a similar approach to that would be good 👍

[kobaji]

My team would like to work on this issue.
The document process.md says non collaborators like me cannot assign myself, but I'll try to assign haha.

/assign @kobaji

[added description]
I did not think that I could assign myself...

[kobaji]

/assign @watanabeyk , my fellow.

[kobaji]

/assign @kobaji

I just thought if I could assign my fellow but I did not manage it.
Anyway I keep assigning myself.