Incorrect compressing of top level objects

[grabofus]

Bug report

Version (complete output of terser -V or specific git commit)

5.15.1

Complete CLI command or minify() options used

{
  module: true,
  compress: true,
  toplevel: true
}

terser input

const obj = {
    value: 'c'
};

export const compare = (x) => x === obj.value;

terser output or error

export const compare=o=>o===obj.value;

Leading to: Uncaught ReferenceError: obj is not defined

Expected result

const c="c";export const compare=o=>o===c;

[grabofus]

For context, both of these work as expected:

const obj = {
    value: 'c'
};

const compare = (x) => x === obj.value;

export { compare }

// Outputs:

const c="c",o=o=>o===c;export{o as compare};

const obj = {
    value: 'c'
};

export default (x) => x === obj.value;

// Outputs:

const t="c";export default c=>c===t;