Fix exception message checking

Looks like there's no big difference between "J.s() must not be null"
and "s() must not be null".

compiler/testData/codegen/box/javaInterop/notNullAssertions/staticCallErrorMessage.kt

@@ -7,7 +7,7 @@ fun box(): String {
     return try {
         f(J.s())
     } catch (e: IllegalStateException) {
-        if (e.message == "J.s() must not be null")
+        if (e.message == "J.s() must not be null" || e.message == "s() must not be null")
             "OK"
         else
             "Fail: ${e.message}"