Added error propagation in Field access

[neeldug]

This Pull Request fixes/closes #482.

It changes the following:

• mod.rs to_object function call error handling to use ? operator

[codecov]

Codecov Report

Merging #500 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #500      +/-   ##
==========================================
+ Coverage   67.62%   67.65%   +0.02%     
==========================================
  Files         160      160              
  Lines        9836     9832       -4     
==========================================
  Hits         6652     6652              
+ Misses       3184     3180       -4     

Impacted Files	Coverage Δ
boa/src/exec/field/mod.rs	100.00% <100.00%> (+26.66%)	⬆️

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[Razican]

Looks perfect, thanks!