Refactor tag handling to use type aliases.

Updated various classes to use `Tags` and `Tag` type aliases instead of generic `Map<String, Any>`. This improves code readability and consistency throughout the codebase.

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

@@ -6,6 +6,9 @@ import io.github.smyrgeorge.log4k.Level.INFO
 import io.github.smyrgeorge.log4k.Level.TRACE
 import io.github.smyrgeorge.log4k.Level.WARN
 import io.github.smyrgeorge.log4k.TracingEvent.Span
+import io.github.smyrgeorge.log4k.impl.MutableTags
+import io.github.smyrgeorge.log4k.impl.Tag
+import io.github.smyrgeorge.log4k.impl.Tags
 import io.github.smyrgeorge.log4k.impl.registry.CollectorRegistry
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.coroutineContext
@@ -84,27 +87,27 @@ abstract class CoLogger(
 
     data class LoggingContext(
         val span: Span?,
-        val attributes: Map<String, Any?>
+        val tags: Tags
     ) : CoroutineContext.Element {
 
         class Builder {
             private var span: Span? = null
-            private var attributes: MutableMap<String, Any?> = mutableMapOf()
+            private var tags: MutableTags = mutableMapOf()
             fun with(span: Span): Builder = apply { this.span = span }
-            fun with(f: (MutableMap<String, Any?>) -> Unit): Builder = apply { f(attributes) }
-            fun with(vararg attributes: Pair<String, Any?>): Builder = apply { this.attributes.putAll(attributes) }
-            fun with(attributes: Map<String, Any?>): Builder = apply { this.attributes.putAll(attributes) }
-            fun build(): LoggingContext = LoggingContext(span, attributes)
+            fun with(f: (MutableTags) -> Unit): Builder = apply { f(tags) }
+            fun with(vararg tags: Tag): Builder = apply { this.tags.putAll(tags) }
+            fun with(tags: Tags): Builder = apply { this.tags.putAll(tags) }
+            fun build(): LoggingContext = LoggingContext(span, tags)
         }
 
         companion object : CoroutineContext.Key<LoggingContext> {
             val EMPTY: LoggingContext = of()
             fun builder(): Builder = Builder()
             fun of(): LoggingContext = LoggingContext(null, emptyMap())
             fun of(span: Span): LoggingContext = LoggingContext(span, emptyMap())
-            fun of(span: Span, attributes: Map<String, Any>): LoggingContext = LoggingContext(span, attributes)
-            fun of(span: Span, vararg attributes: Pair<String, Any>): LoggingContext =
-                LoggingContext(span, attributes.toMap())
+            fun of(span: Span, tags: Tags): LoggingContext = LoggingContext(span, tags)
+            fun of(span: Span, vararg tags: Tag): LoggingContext =
+                LoggingContext(span, tags.toMap())
         }
 
         override val key: CoroutineContext.Key<LoggingContext>

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

@@ -2,8 +2,8 @@ package io.github.smyrgeorge.log4k
 
 import io.github.smyrgeorge.log4k.TracingEvent.Span.Local
 import io.github.smyrgeorge.log4k.TracingEvent.Span.Remote
-import io.github.smyrgeorge.log4k.impl.OpenTelemetry
 import io.github.smyrgeorge.log4k.impl.MutableTags
+import io.github.smyrgeorge.log4k.impl.OpenTelemetry
 import io.github.smyrgeorge.log4k.impl.Tags
 import io.github.smyrgeorge.log4k.impl.extensions.toName
 import kotlinx.datetime.Clock
@@ -187,7 +187,7 @@ sealed interface TracingEvent {
                     tags = tags + mapOf(
                         OpenTelemetry.EXCEPTION_TYPE to error::class.toName(),
                         OpenTelemetry.EXCEPTION_ESCAPED to escaped,
-                        OpenTelemetry.EXCEPTION_MESSAGE to error.message,
+                        OpenTelemetry.EXCEPTION_MESSAGE to (error.message ?: ""),
                         OpenTelemetry.EXCEPTION_STACKTRACE to error.stackTraceToString(),
                     )
                 )
@@ -266,7 +266,7 @@ sealed interface TracingEvent {
         data class Event(
             val name: String,
             val timestamp: Instant,
-            val tags: Map<String, Any?>,
+            val tags: Tags,
         )
 
         // https://opentelemetry.io/docs/specs/otel/trace/api/#set-status

log4k/src/commonMain/kotlin/io/github/smyrgeorge/log4k/impl/appenders/simple/SimpleMeteringCollectorAppender.kt

@@ -3,6 +3,7 @@ package io.github.smyrgeorge.log4k.impl.appenders.simple
 import io.github.smyrgeorge.log4k.Appender
 import io.github.smyrgeorge.log4k.Meter
 import io.github.smyrgeorge.log4k.MeteringEvent
+import io.github.smyrgeorge.log4k.impl.Tags
 import io.github.smyrgeorge.log4k.impl.extensions.toName
 import kotlinx.datetime.Instant
 
@@ -137,7 +138,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
         val kind: Meter.Instrument.Kind
         val unit: String?
         val description: String?
-        val tags: Map<String, Any>?
+        val tags: Tags?
         var value: Number
         var updatedAt: Instant?
 
@@ -157,7 +158,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
             appendLine()
         }
 
-        fun Map<String, Any>.format(): String =
+        fun Tags.format(): String =
             entries.joinToString(prefix = "{", postfix = "}") { (k, v) -> "$k=\"$v\"" }
 
         data class Info(
@@ -169,7 +170,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
 
         abstract class AbstractCounter(
             override val name: String,
-            override val tags: Map<String, Any>?,
+            override val tags: Tags?,
             override val kind: Meter.Instrument.Kind,
             override val unit: String?,
             override val description: String?,
@@ -194,7 +195,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
 
         abstract class AbstractRecorder(
             override val name: String,
-            override val tags: Map<String, Any>?,
+            override val tags: Tags?,
             override val kind: Meter.Instrument.Kind,
             override val unit: String?,
             override val description: String?,
@@ -209,7 +210,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
 
         class Counter(
             name: String,
-            tags: Map<String, Any>?,
+            tags: Tags?,
             kind: Meter.Instrument.Kind,
             unit: String?,
             description: String?,
@@ -219,7 +220,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
 
         class UpDownCounter(
             name: String,
-            tags: Map<String, Any>?,
+            tags: Tags?,
             kind: Meter.Instrument.Kind,
             unit: String?,
             description: String?,
@@ -240,7 +241,7 @@ class SimpleMeteringCollectorAppender : Appender<MeteringEvent> {
 
         class Gauge(
             name: String,
-            tags: Map<String, Any>?,
+            tags: Tags?,
             kind: Meter.Instrument.Kind,
             unit: String?,
             description: String?,

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

@@ -1,4 +1,5 @@
 package io.github.smyrgeorge.log4k.impl
 
+typealias Tag = Pair<String, Any>
 typealias Tags = Map<String, Any>
 typealias MutableTags = MutableMap<String, Any>