Add repro test for issue #52912 nested array assignability

Agent-Logs-Url: https://github.com/RyanCavanaugh/TypeScript/sessions/dee5edef-e472-4317-8876-e1ca781fb3bf

Co-authored-by: RyanCavanaugh <[email protected]>

Author: Copilot

tests/cases/compiler/issue52912.ts

@@ -0,0 +1,23 @@
+// @strict: true
+
+// Repro from #52912
+
+type Source1 = { array: Source2[] };
+type Source2 = { array: Source3[] };
+type Source3 = { array: Source4[] };
+type Source4 = {};
+
+type Target1 = { array: Target2[] };
+type Target2 = { array: Target3[] };
+type Target3 = { array: Target4[] };
+type Target4 = { someNewProperty: string };
+
+declare const source1: Source1;
+declare const source2: Source2;
+declare const source3: Source3;
+declare const source4: Source4;
+
+const target1: Target1 = source1; // Error
+const target2: Target2 = source2; // Error
+const target3: Target3 = source3; // Error
+const target4: Target4 = source4; // Error