NRE in CommandSearcher.GetNextCmdlet

[powercode]

PR Summary

Fixes a NullReferenceException when searching for malformed cmdlet names

PR Context

In GetNextCmdlet, there is a check

if (!useAbbreviationExpansion && PSSnapinQualifiedCommandName == null)
{
    return null;
}

i.e. the null check is only done if useAbbreviationExpansion is false.

Later on we reference PSSnapinQualifiedCommandName in anyway and get an NRE.

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[powercode]

@SteveL-MSFT Can you review? Didn't you add the abbreviation feature?

[iSazonov]

Repo steps:

 gcm a\b\get-qqq* -UseAbbreviationExpansion

Get-Command: Object reference not set to an instance of an object.

[iSazonov]

We could simplify the change:

                    WildcardPattern cmdletMatcher = null;
                    if (PSSnapinQualifiedCommandName != null && PSSnapinQualifiedCommandName.ShortName != null)
                    {
                        cmdletMatcher =
                            WildcardPattern.Get(
                                PSSnapinQualifiedCommandName.ShortName,
                                WildcardOptions.IgnoreCase);
                    }

                    SessionStateInternal ss = _context.EngineSessionState;

                    foreach (List<CmdletInfo> cmdletList in ss.GetCmdletTable().Values)
                    {
                        foreach (CmdletInfo cmdlet in cmdletList)
                        {
                            if ((cmdletMatcher != null && cmdletMatcher.IsMatch(cmdlet.Name)) ||
                                (_commandResolutionOptions.HasFlag(SearchResolutionOptions.FuzzyMatch) &&
                                FuzzyMatcher.IsFuzzyMatch(cmdlet.Name, _commandName)))
                            {
                                if (string.IsNullOrEmpty(PSSnapinQualifiedCommandName?.PSSnapInName) ||
                                    (PSSnapinQualifiedCommandName.PSSnapInName.Equals(
                                        cmdlet.ModuleName, StringComparison.OrdinalIgnoreCase)))

[adityapatwardhan]

@powercode please have a look at failing tests

[ghost]

Hello @iSazonov!

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[ghost]

🎉v7.1.0-preview.4 has been released which incorporates this pull request.:tada:

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