Chicken curry in a slow cooker turns out watery
A slow cooker needs a lot less water for the same recipe than something you simmer in a pan for 20 minutes. The sauce thickens in the pan because a lot of the water evaporates.

In this case, most your water is in the chicken stock. To get all of the flavor, but less moisture, drastically reduce, or even eliminate the stock. You've got plenty of water without it. Use a tsp of chicken base to keep the flavor without the water (recommended: Better Than Bouillon).

That alone will probably solve your problem. If it doesn't, come back to this question and edit it to tell us what you tried and any problems that remain, or ask a new question if the problem is different.

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