The way to check for an undefined value in Perl is

if (defined $value) {
  ...
};
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(see perldoc -f defined for more information). You could also turn off the warning, but usually, turning off a warning is a bad practice because you're likely to forget to turn it on again immediately afterwards.

{
  no warnings 'uninitialized';
  print LOG $process->{ExecutablePath}, "\n";
};
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