Throwing if node-arch is provided on linux and macos (dcodeIO#8)

README.md

@@ -15,6 +15,7 @@ The node.js mirror to use, e.g. `https://nodejs.org/download/v8-canary/` for nod
 ### node-arch (Windows only)
 
 The architecture of node.js to use. Defaults to system arch if omitted. More info about nvm-windows arch modifier [here](https://github.com/coreybutler/nvm-windows#usage).
+Note that the action will reject to run on both GNU/Linux and macOS if node-arch is provided.
 
 ## Example usage:
 

index.js

@@ -25,15 +25,16 @@ async function resolveVersion(version, mirror) {
 (async () => {
   let mirror = core.getInput("node-mirror") || "https://nodejs.org/dist/";
   let version = await resolveVersion(core.getInput("node-version"), mirror);
+  let arch = core.getInput("node-arch") || "";
   if (process.platform == "win32") {
-    let arch = core.getInput("node-arch") || "";
     runScript("powershell", ".\\install.ps1", version, mirror, arch);
   } else {
+    if (arch) throw Error("Invalid input parameter: node-arch");
     runScript("bash", "install.sh", version, mirror);
   }
 })();
 
-// arch only applies to Windows platform, so it's a no-op on GNU/Linux and macOS
+// arch only applies to Windows platform, so it will throw on both GNU/Linux and macOS when provided
 function runScript(shell, script, version, mirror, arch) {
   const child = child_process.spawn(shell, [ script, version, mirror, arch ], { cwd: __dirname });
   const stdout = [];