[LL FIR] fix possible race in cached value reading in ValueWithPostCompute

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/caches/ValueWithPostCompute.kt

@@ -92,7 +92,7 @@ internal class ValueWithPostCompute<KEY, VALUE, DATA>(
                 throw stateSnapshot.error
             }
             else -> {
-                return value as VALUE
+                return stateSnapshot as VALUE
             }
         }
     }