updated check if powershell is available

Author: NickTyrer

modules/exploits/windows/local/wmi_persistence.rb

@@ -64,7 +64,10 @@ def initialize(info = {})
 
 
   def exploit
-   raise "Powershell not available" if ! have_powershell?
+   unless have_powershell?
+      print_error("This module requires powershell to run")
+      return
+   end
 
    unless is_admin?
       print_error("This module requires admin privs to run")
@@ -179,4 +182,4 @@ def cleanup
     file_local_write(clean_rc, clean_up_rc)
     print_status("Clean up Meterpreter RC file: #{clean_rc}")
   end
-end
+end