Fix hls Error when loading first segment

[Leslie-Wong-H]

Fix #186

[codecov]

Codecov Report

Merging #187 (ae2a362) into main (ce0cb51) will not change coverage.
Report is 8 commits behind head on main.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #187   +/-   ##
=======================================
  Coverage   75.00%   75.00%           
=======================================
  Files          12       12           
  Lines         436      436           
  Branches       91       91           
=======================================
  Hits          327      327           
  Misses        104      104           
  Partials        5        5           

Flag	Coverage Δ
unittests	75.00% <100.00%> (ø)

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Files Changed	Coverage Δ
src/lib/generate-video-preview.js	92.72% <100.00%> (ø)