[Issue] SetupLogReviewer doesn't handle logs gracefully

Describe the issue
Getting a failure to run the script because we can't properly determine the last install attempt section. Then fail out the entire script.

Expected behavior
Try to handle these unexpected behaviors better.

Script Output

.\SetupLogReviewer.ps1 "C:\DesktopNonOneDrive\Temp\ExchangeSetup (1)\ExchangeSetup.log"
Setup Log Reviewer Version:
Setup Mode: Upgrade
Setup.exe Run Date: 02/09/2026 08:33:49
Setup.exe Build Number: 15.2.2562.17


----------------Error Information----------------
Test-PrerequisiteCheck : Cannot index into a null array.
Inner Exception:    at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(FunctionContext funcContext, Exception exception)
   at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.Interpreter.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.LightLambda.RunVoid1[T0](T0 arg0)
   at System.Management.Automation.PSScriptCmdlet.RunClause(Action`1 clause, Object dollarUnderbar, Object inputToProcess)
   at System.Management.Automation.PSScriptCmdlet.DoProcessRecord()
   at System.Management.Automation.CommandProcessor.ProcessRecord()
Position Message: At C:\GitHub\CSS-Exchange\Setup\Shared\SetupLogReviewerLogic.ps1:33 char:43
+             $result = $SetupLogReviewer | & $test
+                                           ~~~~~~~
Script Stack: at Test-PrerequisiteCheck<Process>, C:\GitHub\CSS-Exchange\Setup\SetupLogReviewer\Checks\FindContext\Test-PrerequisiteCheck.ps1: line 103
at InvokeTests, C:\GitHub\CSS-Exchange\Setup\Shared\SetupLogReviewerLogic.ps1: line 33
at Invoke-SetupLogReviewer, C:\GitHub\CSS-Exchange\Setup\Shared\SetupLogReviewerLogic.ps1: line 88
at <ScriptBlock>, C:\GitHub\CSS-Exchange\Setup\SetupLogReviewer\SetupLogReviewer.ps1: line 26
at <ScriptBlock>, <No file>: line 1
-------------------------------------------------


WARNING: Ran into an issue with the script. If possible please email the Setup Log to 'ExToolsFeedback@microsoft.com', or at least notify them of the issue.

Additional context
This appears to be similar to a previous issue #716. Need to make sure that we add in a pester test for this and understand why this issue came back.

Start with Setup/SetupLogReviewer/Checks/FindContext/Test-PrerequisiteCheck.ps1 at line 103 and Setup/Shared/SetupLogReviewerLogic.ps1 at line 33, then compare the behavior with previous issue #716. Reproduce the failure using the reported log scenario and add a Pester test for an unrecognized last install attempt section. Done means the reviewer handles that unexpected log behavior without failing the entire script.