returning subjective head if request to trusted peer for head fails

[gupadhyaya]

Fixes #85

[codecov-commenter]

Codecov Report

Merging #87 (690e8b5) into main (87ab66e) will increase coverage by 0.08%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main      #87      +/-   ##
==========================================
+ Coverage   67.27%   67.36%   +0.08%     
==========================================
  Files          35       35              
  Lines        2827     2828       +1     
==========================================
+ Hits         1902     1905       +3     
+ Misses        772      771       -1     
+ Partials      153      152       -1     

Files Changed	Coverage Δ
sync/sync_head.go	63.49% <0.00%> (-0.51%)	:arrow_down:

... and 1 file with indirect coverage changes