Check hasOwnProperty before copying property

src/server/editorServices.ts

@@ -528,9 +528,11 @@ namespace ts.server {
                 // raw is now fixed and ready
                 this.safelist = raw.typesMap;
                 for (const key in raw.simpleMap) {
+                    if (raw.simpleMap.hasOwnProperty(key)) {
                         this.legacySafelist[key] = raw.simpleMap[key].toLowerCase();
                     }
                 }
+            }
             catch (e) {
                 this.logger.info(`Error loading types map: ${e}`);
                 this.safelist = defaultTypeSafeList;