Mastering Windows PowerShell Scripting - Third Edition

Using trap

trap is declared in a similar manner to the catch block:

trap { <script> } 
trap [ExceptionType] { <script> } 
trap [ExceptionType1], [ExceptionType2] { <script> } 

A script may contain more than one trap statement, for example:

trap [InvalidOperationException] { 
    Write-Host 'An invalid operation' 
} 
trap { 
    Write-Host 'Catch all other exceptions' 
} 

The ordering of the preceding trap statements doesn't matter; the statement with the most specific error type is used to handle a given error.

PowerShell, as a script-based language normally executes statements in the order written. However, when using a script, function, or script block, the trap statement can appear anywhere; trap doesn't have to appear before the code it acts against. ...