How does an Erratum on one's own paper affect one's career as a researcher?
It will not affect you career. You'll be fine.

An erratum is not a bad thing, per se. Errors happen, and if you fix them it's fine. The error you describe are totally normal and I would even guess that a large fraction of published paper contains this type of error and does not have an erratum.

Even a more serious error that invalidates some of your finding will not necessarily have any impact on your career (but in this case you should write an erratum!). A retraction would be more serious, because retraction are associated with misconduct.

Another point is, that most people will not even notice that there is as erratum for one of your papers.