fix: Initialize DeviceService.Properties with an empty map

[FelixTing]

Initialize DeviceService.Properties with an empty map to avoid unintended access to a nil map
fix: #1656

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PR Checklist

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• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added unit tests for the new feature or bug fix (if not, why?)
• I have fully tested (add details below) this the new feature or bug fix (if not, why?) currently not used in sdk
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[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 32.78%. Comparing base (21de6ff) to head (89b0421).

Files with missing lines	Patch %	Lines
pkg/service/service.go	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1657      +/-   ##
==========================================
- Coverage   32.79%   32.78%   -0.01%     
==========================================
  Files          48       48              
  Lines        4763     4764       +1     
==========================================
  Hits         1562     1562              
- Misses       3063     3064       +1     
  Partials      138      138              

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[cloudxxx8]

LGTM