You can drill a small (1/8 inch will do) hole on both ends of that crack (just past where the crack ends)...the drilled holes will stop the crack from spreading and going further. If the plastic is white, ( usually is ) I cover the crack with silicone, or many manufactures have some great repair tape for cracked liners....the repair kit tape:
Some manufacture liner repair tips:
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Refrigerator Repair and Maintenance Parts
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