core: ignore debug info with bad variable names

jadx-core/src/main/java/jadx/core/deobf/NameMapper.java

@@ -5,6 +5,8 @@ import java.util.HashSet;
 import java.util.Set;
 import java.util.regex.Pattern;
 
+import static jadx.core.utils.StringUtils.notEmpty;
+
 public class NameMapper {
 
 	private static final Pattern VALID_JAVA_IDENTIFIER = Pattern.compile(
@@ -76,11 +78,15 @@ public class NameMapper {
 	}
 
 	public static boolean isValidIdentifier(String str) {
-		return VALID_JAVA_IDENTIFIER.matcher(str).matches() && isAllCharsPrintable(str);
+		return notEmpty(str)
+				&& VALID_JAVA_IDENTIFIER.matcher(str).matches()
+				&& isAllCharsPrintable(str);
 	}
 
 	public static boolean isValidFullIdentifier(String str) {
-		return VALID_JAVA_FULL_IDENTIFIER.matcher(str).matches() && isAllCharsPrintable(str);
+		return notEmpty(str)
+				&& VALID_JAVA_FULL_IDENTIFIER.matcher(str).matches()
+				&& isAllCharsPrintable(str);
 	}
 
 	public static boolean isPrintableChar(int c) {

jadx-core/src/main/java/jadx/core/dex/nodes/parser/DebugInfoParser.java

@@ -4,6 +4,7 @@ import java.util.List;
 
 import com.android.dex.Dex.Section;
 
+import jadx.core.deobf.NameMapper;
 import jadx.core.dex.attributes.nodes.SourceFileAttr;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.RegisterArg;
@@ -280,7 +281,14 @@ public class DebugInfoParser {
 		}
 
 		if (mergeRequired) {
-			reg.mergeDebugInfo(var.getType(), var.getName());
+			applyDebugInfo(reg, var);
+		}
+	}
+
+	private static void applyDebugInfo(RegisterArg reg, LocalVar var) {
+		String varName = var.getName();
+		if (NameMapper.isValidIdentifier(varName)) {
+			reg.mergeDebugInfo(var.getType(), varName);
 		}
 	}
 }

jadx-core/src/main/java/jadx/core/utils/StringUtils.java

@@ -198,4 +198,8 @@ public class StringUtils {
 			sb.append(c);
 		}
 	}
+
+	public static boolean notEmpty(String str) {
+		return str != null && !str.isEmpty();
+	}
 }