If you have a plow plane, you could plow a groove and let a piece into the groove. You’ll need to figure out a way to guide the plow, though. It looks like you may be close enough to the edge for it to be easy. Ignoring it would be perfectly fine. I agree with Jeff and probably wouldn’t go the filler / epoxy route.
That looks like construction lumber, i.e., softwood. Scrapers don’t work well on softwood and do exactly as you describe.