If you do find yourself with a cracked wrapper, before you chuck it, you can try repairing it with a gelatinous mixture of pectin powder and water.

I had the opposite problem last month where a cigar got wet from an overly-filled humidifier. The filler and binder expanded faster/more than the wrapper and it left a 1 cm by 1 mm crack. After letting it dry out, I just applied the pectin to the wrapper and exposed binder to create a seal and it smoked wonderfully. The crack was near the head and I smoked it to the nub without it unraveling.