fix: set metadata when not provided

[plyr4]

not 100% in love with this solution but we need to be able to set metadata from the worker repo to solve nil panics in tests.

other solutions to consider:

• decoupling worker tests from the compiler, its bad practice to test someone elses code anyways
• move Metadata structs out of internal so that you can use WithMetadata in the worker tests

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 53.04%. Comparing base (4b1893a) to head (6f3a839).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
compiler/native/compile.go	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1189      +/-   ##
==========================================
- Coverage   53.05%   53.04%   -0.01%     
==========================================
  Files         559      559              
  Lines       19740    19742       +2     
==========================================
  Hits        10473    10473              
- Misses       8699     8700       +1     
- Partials      568      569       +1     

Files with missing lines	Coverage Δ
compiler/native/compile.go	71.22% <0.00%> (-0.51%)	⬇️