Refactor LoggingEvent and improve error handling

Changed LoggingEvent from a data class to a regular class. Enhanced error handling in Logger and improved test cases for better exception logging. Also added stack trace printing in ConsoleAppender.

log4k/src/commonMain/kotlin/io/github/smyrgeorge/log4k/Logger.kt

@@ -55,8 +55,9 @@ abstract class Logger {
     fun debug(msg: String, vararg args: Any?): Unit = log(Level.DEBUG, msg, args)
     fun info(msg: String, vararg args: Any?): Unit = log(Level.INFO, msg, args)
     fun warn(msg: String, vararg args: Any?): Unit = log(Level.WARN, msg, args)
-    fun error(msg: String, vararg args: Any?): Unit = log(Level.ERROR, msg, args)
-    fun error(msg: String, throwable: Throwable, vararg args: Any?): Unit = log(Level.ERROR, msg, throwable, args)
+    fun error(msg: String?, vararg args: Any?): Unit = log(Level.ERROR, msg ?: "", args)
+    fun error(msg: String?, throwable: Throwable, vararg args: Any?): Unit =
+        log(Level.ERROR, msg ?: "", throwable, args)
 
     companion object {
         fun of(name: String): Logger = RootLogger.factory.getLogger(name)

log4k/src/commonMain/kotlin/io/github/smyrgeorge/log4k/LoggingEvent.kt

@@ -2,8 +2,7 @@ package io.github.smyrgeorge.log4k
 
 import kotlinx.datetime.Instant
 
-@Suppress("ArrayInDataClass")
-data class LoggingEvent(
+class LoggingEvent(
     var id: Long = 0,
     val level: Level,
     val logger: String,

log4k/src/commonMain/kotlin/io/github/smyrgeorge/log4k/impl/ConsoleAppender.kt

@@ -9,6 +9,7 @@ class ConsoleAppender : Appender {
     override val name: String = this::class.toName()
     override fun append(event: LoggingEvent) {
         print(event.format())
+        event.throwable?.printStackTrace()
     }
 
     private fun LoggingEvent.format(): String {

log4k/src/commonTest/kotlin/io/github/smyrgeorge/log4k/MainTests.kt

@@ -18,12 +18,19 @@ class MainTests {
         log.info("this is a test")
         RootLogger.loggers.mute("io.github.smyrgeorge.log4k.MainTests")
         log.info("this is a test with 1 arg: {}", "hello")
-        RootLogger.loggers.unmute("io.github.smyrgeorge.log4k.MainTests")
+        RootLogger.loggers.unmute(this::class)
         log.info("this is a test with 1 arg: {}", "hello")
 
+        try {
+            error("An error occurred!")
+        } catch (e: Exception) {
+            log.error(e.message)
+            log.error(e.message, e)
+        }
+
         runBlocking {
             withContext(Dispatchers.IO) {
-                delay(1000)
+                delay(2000)
             }
         }
     }