fix: Handle Nullable Map and Enum Mismatch in MarkTextOptions.kt

[anggaprytn]

Fix: Handle Nullable Map and Enum Mismatch in MarkTextOptions.kt

Description

This PR addresses two issues in MarkTextOptions.kt:

1. Nullable ReadableMap handling
   ReadableArray.getMap(index) returns a nullable ReadableMap?, but was passed directly into the TextOptions constructor, which expects a non-null ReadableMap.
   ✅ Fixed using Kotlin's safe call with let { ... }, and explicitly throwing MarkerError if null.

2. Incorrect enum usage
   MarkerError expects the first argument to be of type ErrorCode, but a String literal "NULL_MAP" was passed instead.
   ✅ Fixed by adding a new ErrorCode.NULL_MAP enum value and using it explicitly in the constructor.

Changes

• Added ErrorCode.NULL_MAP to the ErrorCode enum.
• Updated MarkTextOptions.kt to:
  • Safely handle nullable maps from ReadableArray.
  • Throw MarkerError(ErrorCode.NULL_MAP, ...) instead of passing a raw string.

Impact

• Prevents potential NullPointerException during runtime.
• Aligns with Kotlin’s null-safety expectations and improves type correctness.
• No changes in public API or functionality, purely an internal safety fix.

Test

• Build successful
• Tested on Android emulator
• Verified behavior with missing/null watermarkTexts input