Added python error catching

lib/pygments/popen.rb

@@ -255,6 +255,8 @@ def mentos(method, args=[], kwargs={}, original_code=nil)
           # mentos is now waiting for the header, and, potentially, code.
           write_data(out_header, code)
 
+          check_for_error
+
           # mentos will now return data to us. First it sends the header.
           header = get_header
 
@@ -275,6 +277,16 @@ def mentos(method, args=[], kwargs={}, original_code=nil)
     raise MentosError, "EPIPE"
     end
 
+    def check_for_error
+      error_msg = @err.read
+
+      unless error_msg.empty?
+        @log.error "[#{Time.now.iso8601}] Error running python script: #{error_msg}"
+        stop "Error running python script: #{error_msg}"
+        raise MentosError, error_msg
+      end
+    end
+
 
     # Based on the header we receive, determine if we need
     # to read more bytes, and read those bytes if necessary.