+3

. I learned this trick a number of years ago and have since used it quite a bit.
Instead of shavings and sanding dust to try to disguise the existence of a crack (which frequently doesn't work very well anyway), try some alternate approaches to give the crack a more "natural" appearance.
If the crack is large enough, you can simulate a bark inclusion or decayed wood material by using dried used coffee grounds. Sometimes using a blender to turn the grounds into dust is the right solution. Partially fill the crack with coffee grounds by sprinkling them over the crack -- don't try to cram or pack the area or it won't look right. Then using thin CA with a micro tip applicator, gently wick some thin CA into the area. It will readily absorb into the wood and coffee grounds. Then quickly sprinkle a bit more coffee on top to cover up the slight shine that the CA causes. I have used this process a lot and it also works when "replacing" some missing bark.
Another trick is to add a very tiny amount of brown TransFast dye powder to medium CA -- just a very tiny amount -- we want the glue to still be somewhere between transparent and translucent, but definitely not opaque. This works well for very small cracks. You can also make black CA using this method and you might also want to make it opaque. For larger cracks, I have also used TransFast dye powder to color T-88 structural epoxy. Be forewarned that the gel time for the epoxy is about an hour during which time the repaired area has to remain horizontal to avoid runs. Other than using an oven, I don't know of any accelerator for epoxy.
Finally, I have also used epoxy putty (medium and dark wood colored) for repairing large breaks where there was partly decomposed bark inclusions -- this happens frequently in mesquite. Sometimes turning mesquite is somewhat like turning a jigsaw puzzle -- just a bunch of loosely associated parts slightly interlocked until just the right (or wrong, depending on your point of view from where you happen to be standing) cut is made. Using the epoxy putty is nice and sets up in about twenty minutes. However, it requires some carving and coloring skill to "convert" it to realistic looking "wood". I use an X-acto knife and furniture touch up and wood graining pens to sculpt and color my fake wood to match the surrounding wood. This is easier to do on mesquite than it would be on many other wood species.