Merge request widget stays in loading state for removed source project

Steps to reproduce

• open !76163 (merged)

What is the current bug behavior?

error message is shown and merge request widget stays in loading state:

this is caused by pipelines being undefined here and the error not handled

What is the expected correct behavior?

merge request widget is shown

Possible fixes

- this.detatchedPipeline = pipelines.length ? pipelines[0].mergeRequestEventType : null;
+ this.detatchedPipeline = pipelines?.length ? pipelines[0].mergeRequestEventType : null;

may be enough already