refactor: improve multi line warning print

jadx-core/src/main/java/jadx/api/ResourcesLoader.java

@@ -84,7 +84,7 @@ public final class ResourcesLoader {
 			LOG.error("Decode error", e);
 			CodeWriter cw = new CodeWriter();
 			cw.add("Error decode ").add(rf.getType().toString().toLowerCase());
-			cw.startLine(Utils.getStackTrace(e.getCause()));
+			Utils.appendStackTrace(cw, e.getCause());
 			return ResContainer.textResource(rf.getName(), cw);
 		}
 	}

jadx-core/src/main/java/jadx/core/codegen/ClassGen.java

@@ -263,7 +263,7 @@ public class ClassGen {
 			} catch (Exception e) {
 				code.newLine().add("/*");
 				code.newLine().addMultiLine(ErrorsCounter.methodError(mth, "Method generation error", e));
-				code.newLine().addMultiLine(Utils.getStackTrace(e));
+				Utils.appendStackTrace(code, e);
 				code.newLine().add("*/");
 				code.setIndent(savedIndent);
 				mth.addError("Method generation error: " + e.getMessage(), e);

jadx-core/src/main/java/jadx/core/codegen/CodeWriter.java

@@ -97,10 +97,12 @@ public class CodeWriter {
 	}
 
 	public CodeWriter addMultiLine(String str) {
-		buf.append(str);
 		if (str.contains(NL)) {
+			buf.append(str.replace(NL, NL + indentStr));
 			line += StringUtils.countMatches(str, NL);
 			offset = 0;
+		} else {
+			buf.append(str);
 		}
 		return this;
 	}

jadx-core/src/main/java/jadx/core/dex/visitors/regions/CheckRegions.java

@@ -84,8 +84,8 @@ public class CheckRegions extends AbstractVisitor {
 
 	private static String getBlockInsnStr(MethodNode mth, IBlock block) {
 		CodeWriter code = new CodeWriter();
+		code.incIndent();
 		code.newLine();
-		code.setIndent(3);
 		MethodGen mg = MethodGen.getFallbackMethodGen(mth);
 		InsnGen ig = new InsnGen(mg, true);
 		for (InsnNode insn : block.getInstructions()) {
@@ -95,7 +95,7 @@ public class CheckRegions extends AbstractVisitor {
 				// ignore
 			}
 		}
-		code.newLine().addIndent();
+		code.newLine();
 		code.finish();
 		return code.toString();
 	}