Error: Cannot find module '${HOME}/host.js'

[justfortherec]

I am unable to connect Firefox with the native client because the path to host.js in the run.sh script is not found.

This is the error message that I see in the browser console:

NS_ERROR_ILLEGAL_VALUE: Component returned failure code: 0x80070057 (NS_ERROR_ILLEGAL_VALUE) [nsINativeMessagingPortal.closeSession] [NativeMessaging.jsm:360](resource://gre/modules/NativeMessaging.jsm)
stderr output from native app com.add0n.node: node:internal/modules/cjs/loader:998
stderr output from native app com.add0n.node:   throw err;
stderr output from native app com.add0n.node:   ^
stderr output from native app com.add0n.node: 
stderr output from native app com.add0n.node: Error: Cannot find module '${HOME}/host.js'
stderr output from native app com.add0n.node:     at Module._resolveFilename (node:internal/modules/cjs/loader:995:15)
stderr output from native app com.add0n.node:     at Module._load (node:internal/modules/cjs/loader:841:27)
stderr output from native app com.add0n.node:     at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
stderr output from native app com.add0n.node:     at node:internal/main/run_main_module:23:47 {
stderr output from native app com.add0n.node:   code: 'MODULE_NOT_FOUND',
stderr output from native app com.add0n.node:   requireStack: []
stderr output from native app com.add0n.node: }
stderr output from native app com.add0n.node: 
stderr output from native app com.add0n.node: Node.js v18.12.1
OperationError: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: Object does not exist at path “/org/freedesktop/portal/desktop/session/1_3947/firefox_com_add0n_node_4064532493”

(Note that I've replaced the actual path to my home directory with ${HOME} when copying the message)

It appears that Firefox starts the native client from $HOME as the working directory.
That leads to the script resolving the relative path host.js as $HOME/host.js.

I was able to fix this by applying the following tiny patch to run.sh:

 #!/usr/bin/env bash
-/usr/bin/node host.js
+/usr/bin/node $(dirname "$0")/host.js

This prefixes the host.js filename with the directory of the run.sh file — regardless of the working directory and regardless of the directory in which run.sh and the JavaScript files are located (as long as they are in the same location).