You cannot call a method on a null-valued expression.

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You cannot call a method on a null-valued expression.
At line:36 char:5
+     $output = $process.StandardOutput.ReadToEnd()
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull
 
ConvertFrom-Json : Cannot bind argument to parameter 'InputObject' because it is null.
At line:39 char:27
+         $json = $output | ConvertFrom-Json
+                           ~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [ConvertFrom-Json], ParameterBindingValidationException
    + FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.ConvertFromJsonCommand