parse-opti-logs.ps1

# Input / Output
$inputPath  = ".\h=20\m=00\PT1H.json"
$outputPath = ".\h=20\m=00\PT1H-resultDescription.txt"

Get-Content -LiteralPath $inputPath |
  ForEach-Object {
    try {
      ($_.Trim() | ConvertFrom-Json).resultDescription
    }
    catch {
      $null  # skip malformed lines
    }
  } |
  Where-Object { $_ -ne $null } |
  ForEach-Object { $_.TrimEnd() } |
  Set-Content -LiteralPath $outputPath -Encoding UTF8