typescript variable ‘x’ is used before being assigned

I need to push the result object in an array. But typescript is showing an error

TSError: тип Unable to compile TypeScript:
test.ts:15:10 - error TS2454: Variable 'x' is used before being assigned.

15   return x;
            ~
            

This is my code. I don’t know to declare a global variable in typescript

import * as fs from "fs";
import * as path from "path";
import * as csv from "fast-csv";

function search_words(word: string) {
  var x: object[];
  fs.createReadStream(path.resolve(__dirname, ".", "data", "data.csv"))
    .pipe(csv.parse({ headers: true }))
    .on("error", (error) => console.error(error))
    .on("data", (row) => {
      if (row.english_word === word) x.push(row);
    })
    .on("end", (rowCount: number) => console.log(`Parsed ${rowCount} rows`));

  return x;
}

console.log(search_words("Hello"));

This method is I know.any other method is possible

let hi; // global variable
function hello{
hi = "hi mom"
}