Budgets silently fail when there is no "parent build"

[OliverJAsh]

Problem

When using budgets, if there is no parent build and the artifacts from the current build fail the defined budgets, comparator will not complain.

I suspect this is because of

build-tracker/src/comparator/src/index.ts

Line 237 in 8f1df8c

return this.builds.slice(0, i).map(prevBuild => {

Most of the time this won't be an issue, as there will be a parent build, but it could confuse people (like me) who are just getting started with this tool.

I guess it doesn't make sense to run delta budgets when there is no parent build, but it does make sense to run standard size budgets?

Expected Result

Here's what I expect to see when I run the above:

Actual Result

Here's what I actually see when I run the above: