core: fix class cast exception

jadx-core/src/test/java/jadx/tests/internal/arith/TestFieldIncrement.java

@@ -1,4 +1,4 @@
-package jadx.tests.internal;
+package jadx.tests.internal.arith;
 
 import jadx.api.InternalJadxTest;
 import jadx.core.dex.nodes.ClassNode;

jadx-core/src/test/java/jadx/tests/internal/arith/TestFieldIncrement2.java

@@ -0,0 +1,40 @@
+package jadx.tests.internal.arith;
+
+import jadx.api.InternalJadxTest;
+import jadx.core.dex.nodes.ClassNode;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertThat;
+
+public class TestFieldIncrement2 extends InternalJadxTest {
+
+	class A {
+		int f = 5;
+	}
+
+	public static class TestCls {
+		public A a;
+
+		public void test1(int n) {
+			this.a.f = this.a.f + n;
+		}
+
+		public void test2(int n) {
+			this.a.f *= n;
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+		System.out.println(code);
+
+		assertThat(code, containsString("this.a.f += n;"));
+		assertThat(code, containsString("a.f *= n;"));
+		// TODO
+		// assertThat(code, containsString("this.a.f *= n;"));
+	}
+}