fix: handle move-result after invoke-custom with string concat

jadx-core/src/main/java/jadx/core/dex/visitors/ProcessInstructionsVisitor.java

@@ -80,6 +80,13 @@ public class ProcessInstructionsVisitor extends AbstractVisitor {
 					}
 					break;
 
+				case STR_CONCAT:
+					// invoke-custom with string concatenation translated directly to STR_CONCAT, merge next move-result
+					if (insn.getResult() == null) {
+						mergeMoveResult(insnByOffset, offset, insn, ArgType.STRING);
+					}
+					break;
+
 				case FILLED_NEW_ARRAY:
 					ArgType arrType = ((FilledNewArrayNode) insn).getArrayType();
 					mergeMoveResult(insnByOffset, offset, insn, arrType);

jadx-core/src/test/java/jadx/tests/api/IntegrationTest.java

@@ -47,6 +47,7 @@ import jadx.core.utils.files.FileUtils;
 import jadx.core.xmlgen.ResourceStorage;
 import jadx.core.xmlgen.entry.ResourceEntry;
 import jadx.tests.api.compiler.DynamicCompiler;
+import jadx.tests.api.compiler.JavaUtils;
 import jadx.tests.api.compiler.StaticCompiler;
 import jadx.tests.api.utils.TestUtils;
 
@@ -490,6 +491,7 @@ public abstract class IntegrationTest extends TestUtils {
 	}
 
 	protected void useTargetJavaVersion(int version) {
+		Assumptions.assumeTrue(JavaUtils.checkJavaVersion(version), "skip test for higher java version");
 		this.targetJavaVersion = version;
 	}
 

jadx-core/src/test/java/jadx/tests/integration/others/TestStringConcatJava11.java

@@ -3,6 +3,8 @@ package jadx.tests.integration.others;
 import org.junit.jupiter.api.Test;
 
 import jadx.tests.api.RaungTest;
+import jadx.tests.api.extensions.inputs.InputPlugin;
+import jadx.tests.api.extensions.inputs.TestWithInputPlugins;
 
 import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
 
@@ -40,7 +42,7 @@ public class TestStringConcatJava11 extends RaungTest {
 	}
 
 	@Test
-	public void testJava() {
+	public void testJava8() {
 		noDebugInfo();
 		assertThat(getClassNode(TestCls.class))
 				.code()
@@ -49,4 +51,14 @@ public class TestStringConcatJava11 extends RaungTest {
 						"return str + \"test\" + str + 7;",
 						"return str + \"test\" + str + \"7\";"); // dynamic concat add const to string recipe
 	}
+
+	@TestWithInputPlugins({ InputPlugin.DEX, InputPlugin.JAVA })
+	public void testJava11() {
+		useTargetJavaVersion(11);
+		noDebugInfo();
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsOne("return str + \"test\";")
+				.containsOne("return str + \"test\" + str + \"7\";");
+	}
 }

jadx-plugins/jadx-java-convert/src/main/java/jadx/plugins/input/javaconvert/JavaConvertLoader.java

@@ -158,9 +158,13 @@ public class JavaConvertLoader {
 
 		try {
 			DxConverter.run(path, tempDirectory);
-		} catch (Exception e) {
+		} catch (Throwable e) {
 			LOG.warn("DX convert failed, trying D8, path: {}", path);
-			D8Converter.run(path, tempDirectory);
+			try {
+				D8Converter.run(path, tempDirectory);
+			} catch (Throwable ex) {
+				LOG.error("D8 convert failed: {}", ex.getMessage());
+			}
 		}
 
 		LOG.debug("Converted to dex: {}", path.toAbsolutePath());