Bugfix/devtools null signal name

[nank1ro]

Fix DevTools extension with null signal name

[codecov]

Codecov Report

Merging #83 (18c53cd) into main (ce91bfc) will not change coverage.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #83   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           21        21           
  Lines         1243      1244    +1     
=========================================
+ Hits          1243      1244    +1     

Files	Coverage Δ
...ckages/solidart/lib/src/core/collections/list.dart	100.00% <100.00%> (ø)
...ackages/solidart/lib/src/core/collections/map.dart	100.00% <100.00%> (ø)
...ackages/solidart/lib/src/core/collections/set.dart	100.00% <100.00%> (ø)
packages/solidart/lib/src/core/computed.dart	100.00% <100.00%> (ø)
packages/solidart/lib/src/core/effect.dart	100.00% <100.00%> (ø)
packages/solidart/lib/src/core/read_signal.dart	100.00% <100.00%> (ø)
packages/solidart/lib/src/core/resource.dart	100.00% <100.00%> (ø)
packages/solidart/lib/src/core/signal.dart	100.00% <100.00%> (ø)
packages/solidart/lib/src/core/signal_options.dart	100.00% <ø> (ø)