stderr output from native app classifier: ModuleNotFoundError: No module named ‘nltk’

While trying to send/receive data using native messaging between javascript and python for a firefox extension I keep running into the following error in the browser console-

stderr output from native app classifier: ModuleNotFoundError: No module named ‘nltk’

I have installed nltk in my pycharm virtual environment. I want to use nltk for some text processing in the python file used for native messaging. I dont get any error messages for other packages like sys, json, struct. But I get error messages for nltk, keras. But there is no error for pandas!!

Native messaging works fine when I dont import nltk into python.

Following is the python code. I have not shared nltk part of the code here

import sys
import json
import struct
import nltk


class Informationtransmission:

    def getMessage(self):
        rawLength = sys.stdin.buffer.read(4)
        if len(rawLength) == 0:
            sys.exit(0)
        messageLength = struct.unpack('@I', rawLength)[0]
        message = sys.stdin.buffer.read(messageLength).decode('utf-8')
        return json.loads(message)

    def encodeMessage(self, messageContent):
        encodedContent = json.dumps(messageContent).encode('utf-8')
        encodedLength = struct.pack('@I', len(encodedContent))
        return {'length': encodedLength, 'content': encodedContent}

    def sendMessage(self, encodedMessage):
        sys.stdout.buffer.write(encodedMessage['length'])
        sys.stdout.buffer.write(encodedMessage['content'])
        sys.stdout.buffer.flush()

x = Informationtransmission()
receivedMessage = x.getMessage()

if receivedMessage:
    x.sendMessage(x.encodeMessage(receivedMessage))

js file

function logTabs(tabs) {
    let tab = tabs[0];

    port.postMessage(tab.url);
}

function listTabs() {
    browser.tabs.query({currentWindow: true, active: true}).then(logTabs, console.error);
}

let port = browser.runtime.connectNative("classifier");

document.addEventListener("click", (e) => {
    if (e.target.id === "url") {
        listTabs();
    }
})

port.onMessage.addListener((response) => {
    console.log("Received: " + response);
});

addon manifest.json file-

{
    "browser_specific_settings": {
        "gecko": {
            "id": "[e-mail]",
          "strict_min_version": "58.0a1"
        }
    },

    "manifest_version": 2,
    "name": "classifier",
    "version": "1.0",

    "description": "Classifies",

    "background": {
        "scripts": ["popup.js"]
    },

    "browser_action":{
        "browser_style": true,
        "default_icon":{
            "48":"/icon.svg"
        },
        "default_title":"classifier",
        "default_popup":"/popup.html"
    },

    "permissions": [
        "tabs",
        "activeTab",
        "scripting",
        "nativeMessaging"
    ]
}

following are the bat and json file for native app-

@echo off

call python -u "E:projsend_recieve_info.py"

{
  "name": "classifier",
  "description": "host for native messaging",
  "path": "E:\proj\calltoscript.bat",
  "type": "stdio",
  "allowed_extensions": ["[e-mail]"]
}

Answer

Actually I got it. The path that python was pointing to did not have nltk and keras. The plugin was using python from system path not from the virtual environment as I thought.