fix: don't emit package-lock.json when package.json does not exist

workspaces/arborist/lib/arborist/reify.js

@@ -1447,6 +1447,10 @@ module.exports = cls => class Reifier extends cls {
       }
     }
 
+    const isObjectEmpty = (obj) => {
+      return Object.keys(obj).length === 0 && obj.constructor === Object
+    }
+
     // before now edge specs could be changing, affecting the `requires` field
     // in the package lock, so we hold off saving to the very last action
     if (this[_usePackageLock]) {
@@ -1457,10 +1461,12 @@ module.exports = cls => class Reifier extends cls {
       }
 
       // TODO this ignores options.save
-      await this.idealTree.meta.save({
-        format: (this[_formatPackageLock] && format) ? format
-        : this[_formatPackageLock],
-      })
+      if (!isObjectEmpty(this.idealTree.package)) {
+        await this.idealTree.meta.save({
+          format: (this[_formatPackageLock] && format) ? format
+          : this[_formatPackageLock],
+        })
+      }
     }
 
     process.emit('timeEnd', 'reify:save')