With tiled sensors, the fix is usually software correction, not a truly seamless raw capture.

If the missing areas are very narrow, they can be filled for display purposes using interpolation from neighboring pixels. A simple form is nearest-neighbor style healing; more refined methods use weighted values from surrounding pixels. This is similar to how some cameras have corrected thin bad pixel columns that would otherwise show up as black lines.

So yes, visible gaps or lines in astronomy images can often be reduced or removed in processed images. But that does not mean the original sensor data contained real image information in those missing strips. For scientific measurement, you generally would not want to treat interpolated data as if it were genuine captured data. For presentation or “pretty picture” use, though, software healing is common and can work well when the gaps are small.