fix: use default node url if the user happens to explicitly set []

docs/Core.md

@@ -102,7 +102,7 @@ Defaults to `{}`
 
 <h4 id="node_repositories-node_urls">node_urls</h4>
 
-(*List of strings*): custom list of URLs to use to download NodeJS
+(*List of strings*): List of URLs to use to download Node.js.
 
 Each entry is a template for downloading a node distribution.
 

nodejs/repositories.bzl

@@ -9,6 +9,9 @@ load("//nodejs/private:toolchains_repo.bzl", "PLATFORMS", "toolchains_repo")
 # created by the module extension
 DEFAULT_NODE_REPOSITORY = "nodejs"
 
+# Default Node.js URL used as the default for node_urls
+DEFAULT_NODE_URL = "https://nodejs.org/dist/v{version}/{filename}"
+
 # Currently v18 is the "active" LTS release:
 # https://nodejs.dev/en/about/releases/
 # We can only change that in a major release of rules_nodejs,
@@ -92,10 +95,8 @@ By default, if this attribute has no items, we'll use a list of all public NodeJ
 """,
     ),
     "node_urls": attr.string_list(
-        default = [
-            "https://nodejs.org/dist/v{version}/{filename}",
-        ],
-        doc = """custom list of URLs to use to download NodeJS
+        default = [DEFAULT_NODE_URL],
+        doc = """List of URLs to use to download Node.js.
 
 Each entry is a template for downloading a node distribution.
 
@@ -166,6 +167,9 @@ def _download_node(repository_ctx):
         return
 
     node_urls = repository_ctx.attr.node_urls
+    if not node_urls:
+        # Go back the default if the user explicitly specifies []
+        node_urls = [DEFAULT_NODE_URL]
 
     # Download node & npm
     version_host_os = "%s-%s" % (node_version, host_os)