[main] Split formatting for Throwable from formatter with message

src/main/java/io/gitlab/jfronny/commons/log/Logger.java

@@ -100,13 +100,17 @@ public interface Logger {
 
     default String format(String msg, Throwable t) {
         if (t == null) return msg;
+        return msg + System.lineSeparator() + format(t);
+    }
+
+    default String format(Throwable t) {
         try (ByteArrayOutputStream baot = new ByteArrayOutputStream()) {
             try (PrintStream ps = new PrintStream(baot, true)) {
                 t.printStackTrace(ps);
             }
-            return msg + System.lineSeparator() + baot;
+            return baot.toString();
         } catch (IOException e) {
-            return msg + System.lineSeparator() + t;
+            return t.toString();
         }
     }
 }