`Unexpected token : in JSON at position 3` for rc builds

[richardlau]

As part of nodejs/build#3524 I've manually run the promotion script on the non-release builds, and I've noticed lots of errors like the following for the rc builds:

SyntaxError: Unexpected token : in JSON at position 3
    at JSON.parse (<anonymous>)
    at /usr/lib/node_modules/nodejs-dist-indexer/dist-indexer.js:119:19
    at BufferListStream._callback (/usr/lib/node_modules/nodejs-dist-indexer/dist-indexer.js:101:5)
    at BufferListStream.end (/usr/lib/node_modules/nodejs-dist-indexer/node_modules/bl/bl.js:65:10)
    at DestroyableTransform.onend (/usr/lib/node_modules/nodejs-dist-indexer/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:523:10)
    at Object.onceWrapper (node:events:627:28)
    at DestroyableTransform.emit (node:events:525:35)
    at /usr/lib/node_modules/nodejs-dist-indexer/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:965:16
    at processTicksAndRejections (node:internal/process/task_queues:78:11)
(ignoring error fetching npm version for node/v0.10.44-rc.1)

My guess would be that e.g. v0.10.44-rc.1 isn't mapping to a valid git reference when the substitution is done for

nodejs-dist-indexer/dist-indexer.js

Lines 20 to 22 in 860a8b4

	// needs auth: githubContentUrl = 'https://api.github.com/repos/nodejs/node/contents'
	const githubContentUrl = 'https://raw.githubusercontent.com/nodejs/{repo}/{gitref}'
	const npmPkgJsonUrl = `${githubContentUrl}/deps/npm/package.json`

to fetch the package.json file for npm.

[richardlau]

Further evidence, looking at index.json for the rc downloads, most of the version information is either the empty string or null:
e.g.

    {
        "version": "v20.0.0-rc.1",
        "date": "2023-04-13",
        "files": [
            "aix-ppc64",
            "headers",
            "linux-arm64",
            "linux-armv7l",
            "linux-ppc64le",
            "linux-s390x",
            "linux-x64",
            "osx-arm64-tar",
            "osx-x64-pkg",
            "osx-x64-tar",
            "src",
            "win-arm64-7z",
            "win-arm64-zip",
            "win-x64-7z",
            "win-x64-exe",
            "win-x64-msi",
            "win-x64-zip",
            "win-x86-7z",
            "win-x86-exe",
            "win-x86-msi",
            "win-x86-zip"
        ],
        "v8": "",
        "uv": "",
        "zlib": null,
        "openssl": null,
        "modules": null,
        "lts": false,
        "security": false
    },