diagnostics_channel: hasSubscribers throw TypeError: WeakRefPrototypeGet is not a function on Node 15.4.0

[Lxxyx]

I was trying to improve the test coverage of diagnostics_channel and found this issue.

• Version: 15.4.0
• Platform: macOS 10.15.7
• Subsystem: diagnostics_channel

What steps will reproduce the bug?

const diagnostics_channel = require('diagnostics_channel');
const dc = diagnostics_channel.channel('test');
diagnostics_channel.hasSubscribers('test');

How often does it reproduce? Is there a required condition?

Everytime.

What is the expected behavior?

No errors

What do you see instead?

node:diagnostics_channel:110
  if (ref) channel = WeakRefPrototypeGet(ref);
                     ^

TypeError: WeakRefPrototypeGet is not a function
    at Object.hasSubscribers (node:diagnostics_channel:110:22)
    at Object.<anonymous> (/tempCodeRunnerFile.javascript:3:21)
    at Module._compile (node:internal/modules/cjs/loader:1108:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1137:10)
    at Module.load (node:internal/modules/cjs/loader:973:32)
    at Function.Module._load (node:internal/modules/cjs/loader:813:14)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:76:12)
    at node:internal/main/run_main_module:17:47

Additional information

I'm working on this issue. When finished I will send a Pull Request.