fix: reject a duration sum that wraps past 2^64

[SashaMIT]

ParseDuration("9223372036854775808ns 9223372036854775808ns") returned 0s. Each token is 1<<63 nanoseconds. The uint64 sum wraps to 0, and 0 is not greater than maxUint64 (1<<63), so the range check accepts it. The negative pair returned 0s as well.

A single 9223372036854775808ns still errors. -9223372036854775808ns stays the minimum duration. 9000000000000ms 9000000000000ms still errors.

Red: parsed as 0s. Green: go test .

[fredbi]

Thanks. Will review this later today

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.13%. Comparing base (2c2378a) to head (3a19273).
⚠️ Report is 2 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #312   +/-   ##
=======================================
  Coverage   89.13%   89.13%           
=======================================
  Files          24       24           
  Lines        2926     2928    +2     
=======================================
+ Hits         2608     2610    +2     
  Misses        317      317           
  Partials        1        1           

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[fredbi]

Thanks. Good catch