fix readuntil when stream is empty

[bicycle1885]

No description provided.

[codecov-io]

Codecov Report

Merging #74 into master will increase coverage by 0.22%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #74      +/-   ##
==========================================
+ Coverage   77.35%   77.58%   +0.22%     
==========================================
  Files          11       11              
  Lines         636      638       +2     
==========================================
+ Hits          492      495       +3     
+ Misses        144      143       -1

Impacted Files	Coverage Δ
src/stream.jl	76.14% <100%> (+0.42%)	⬆️

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