Set $ErrorActionPreference to Stop in PowerShell function templates code

[AnatoliB]

Problem

By PowerShell design, the default value of $ErrorActionPreference is 'Continue'. New PowerShell users who are not familiar with the concept of non-terminating errors often get confused by the result: the PowerShell function execution seems to be completed successfully but has not in fact performed what it was supposed to perform, and the only way to notice this is to look at the logs.

This problem occasionally affects even experienced PowerShell users, and it seems to be a frequent annoyance for beginners, so it is worth mitigating. At the same time, we don't want to surprise experienced PowerShell users with by modifying the default behavior or introducing any other breaking changes, and we want to avoid creating Functions-specific abstractions on top of PowerShell.

Proposal

When a new PowerShell function is added from a template, the auto-generated code should include the following:

# By default, stop on any error
# (for more details, see <link to the doc, e.g. https://docs.microsoft.com/powershell/module/microsoft.powershell.core/about/about_preference_variables#erroractionpreference>)
$ErrorActionPreference = 'Stop'

As a result, this will make users aware of the difference between terminating vs. non-terminating errors, invite them to learn more if interested, and set a more intuitively expected behavior. At the same time, users familiar with PowerShell who insist on any different behavior will have an opportunity to review, change, or delete this code.

[JustinGrote]

Makes sense to me and wouldn't be a breaking change unless someone has some edge case where they are doing code generation off the existing templates and expecting a certain behavior (pretty unlikely)

[anirudhgarg]

@AnatoliB are we planning to add this to the profile.ps1 ?

[AnatoliB]

@anirudhgarg I was actually thinking about run.ps1 instead. Technically, both profile.ps1 and run.ps1 would work. However, the decision to use a non-default $ErrorActionPreference should normally be coupled with the content of a specific script, i. e. you would want to author your script differently depending on the $ErrorActionPreference value. Also, profile.ps1 is more implicit and less visible. I doubt many PowerShell users set $ErrorActionPreference in their profile.ps1 (probably for the same reasons), so I would just follow the existing practice.

[JustinGrote]

My vote is for profile.ps1 by default in a new function. Most functions are so short lived you want them to "fail fast" and not generate a bunch of non-terminating exceptions