Fix NPE and eager evaluation in traceEntry (Fixes #101)

[SpaceLeam]

Fixes #101

Description

noticed that Logger.traceEntry was eagerly evaluating .toString on arguments and didn't check for nulls, which caused NPEs even when tracing was disabled.

In this PR, I've updated Logger.scala (for both Scala 2 and 3) to:

• Check delegate.isTraceEnabled first (lazy evaluation).
• Add a null check for params.head.

I also added unit tests in LoggerTest.scala to verify that passing null or an object with a throwing toString no longer crashes the application.

Verification

Ran ./mvnw clean test on both modules and everything passed.