fix: Handle module paths pointing to a directory

Author: palant

lib/io.js

@@ -53,6 +53,15 @@ export function readScript(filepath)
 
 export function saveScript(ast, filepath)
 {
+  ensureParentDirExists(filepath);
+
+  let stat = fs.statSync(filepath, {throwIfNoEntry: false});
+  if (stat && stat.isDirectory())
+  {
+    saveScript(ast, path.join(filepath, "index.js"));
+    return;
+  }
+
   let code = astToCode(ast, {
     format: {
       indent: {
@@ -64,6 +73,5 @@ export function saveScript(ast, filepath)
     comment: true
   });
 
-  ensureParentDirExists(filepath);
   fs.writeFileSync(filepath, code, {encoding: "utf-8"});
 }