exit installer if agent is installed

Install-LiquidFilesOutlookAgent.ps1

@@ -1,6 +1,21 @@
 # Path to the MSI installer
 $MSIURL = 'https://lfupdate.s3.amazonaws.com/clients/outlook/admin_msi/LiquidFiles_Admin_2.1.10.msi'
 
+# Get path to the installed agent
+$PathToAgentExe64 = "${Env:ProgramFiles(x86)}\LiquidFiles Windows Agent\LiquidFilesWindowsAgent.exe"
+$PathToAgentExe32 = "${Env:ProgramFiles}\LiquidFiles Windows Agent\LiquidFilesWindowsAgent.exe"
+If ( Test-Path $PathToAgentExe64 ) {
+    $PathToAgentExe = $PathToAgentExe64
+} ElseIf ( Test-Path $PathToAgentExe32 ) {
+    $PathToAgentExe = $PathToAgentExe32
+}
+
+# Exit this script if the agent is already installed
+If ( Test-Path $PathToAgentExe ) {
+    LogMsg "LiquidFiles agent is already installed. This installer will exit."
+    Exit
+}
+
 # Set installer args
 If (-not [string]::IsNullOrEmpty($LFHost) ) {
     LogMsg "LiquidFiles target server: ${LFHost}"
@@ -29,13 +44,6 @@ Try {
 Catch { LogErr $_.Exception.Message }
 
 # Start the agent
-$PathToAgentExe64 = "${Env:ProgramFiles(x86)}\LiquidFiles Windows Agent\LiquidFilesWindowsAgent.exe"
-$PathToAgentExe32 = "${Env:ProgramFiles}\LiquidFiles Windows Agent\LiquidFilesWindowsAgent.exe"
-If ( Test-Path $PathToAgentExe64 ) {
-    $PathToAgentExe = $PathToAgentExe64
-} ElseIf ( Test-Path $PathToAgentExe32 ) {
-    $PathToAgentExe = $PathToAgentExe32
-}
 If ($PathToAgentExe) {
     LogMsg "Starting LiquidFiles agent"
     Try { Start-Process $PathToAgentExe }