bin/p-lang in p-lang-0.0.3 vs bin/p-lang in p-lang-0.0.4

@@ -3,11 +3,14 @@
 require File.join(File.expand_path(File.dirname(__FILE__)), '/../lib/p-lang')
 
 if ARGV[0]
   @parser = PLangParser.new
   
-  ast = @parser.parse(File.readlines(ARGV[0]).join("")).build.collect(&:to_sexp)
-  
-  vm = PLang::VM.new(ast)
-  
-  vm.execute!
-end
\ No newline at end of file
+  ast = @parser.parse(File.readlines(ARGV[0]).join(""))
+
+  if ast
+    vm = PLang::VM.new(ast.build.collect(&:to_sexp))
+    vm.execute!
+  else
+    puts @parser.failure_reason
+  end
+end