bin/slideit in slideit-0.1.0 vs bin/slideit in slideit-0.1.1

@@ -25,10 +25,16 @@
 
 #puts "options is #{options.inspect}"
 #puts "ARGV is #{ARGV.inspect}"
 
 if ARGV.size == 0
-  puts "Please input slide-file"
+  puts "Please input slide file!"
   exit(1)
 else
-  Slideit.show ARGV[0], options
+  file = ARGV[0]
+  if FileTest.file? file
+    Slideit.show file, options
+  else
+    puts "#{file} does not exist!"
+    exit(1)
+  end
 end