M #-: Fix rare failure driver actions (#3693)

* Return empty string if output is nill
* Catch exception in TM driver

Author: paczerny

src/mad/ruby/CommandManager.rb

@@ -210,7 +210,7 @@ def capture3_timeout(*cmd)
             raise terminator_e if terminator_e
 
             # return values
-            [out_reader.value, err_reader.value, t.value]
+            [out_reader.value || '', err_reader.value || '', t.value]
         end
     end
 

src/tm_mad/one_tm.rb

@@ -75,21 +75,25 @@ def initialize(tm_type, options = {})
     # Driver Action: TRANSFER id script_file
     # Executes a transfer script
     def action_transfer(id, script_file)
-        script = parse_script(script_file)
-        if script.nil?
-            return send_message('TRANSFER', RESULT[:failure], id,
-                                "Transfer file '#{script_file}' does not exist")
-        end
+        begin
+            script = parse_script(script_file)
+            if script.nil?
+                return send_message('TRANSFER', RESULT[:failure], id,
+                                    "Transfer file '#{script_file}' does not exist")
+            end
 
-        script.each do |command|
-            result, info = do_transfer_action(id, command)
+            script.each do |command|
+                result, info = do_transfer_action(id, command)
 
-            if result == RESULT[:failure]
-                return send_message('TRANSFER', result, id, info)
+                if result == RESULT[:failure]
+                    return send_message('TRANSFER', result, id, info)
+                end
             end
-        end
 
-        send_message('TRANSFER', RESULT[:success], id)
+            send_message('TRANSFER', RESULT[:success], id)
+        rescue StandardError => e
+            send_message('TRANSFER', RESULT[:failure], id, e.message)
+        end
     end
 
     # Executes a single transfer action (command), as returned by the parse