feat: throw an error when using a TS feature when it isn't avaliable

Author: RebeccaStevens

lib/rules/no-sync.js

@@ -124,19 +124,23 @@ module.exports = {
                         continue
                     }
 
-                    if (parserServices !== null) {
-                        const type = getTypeOfNode(node, parserServices)
-                        if (
-                            typeMatchesSpecifier(
-                                parserServices.program,
-                                ignore,
-                                type
-                            ) &&
-                            (ignore.name === undefined ||
-                                ignore.name.includes(node.name))
-                        ) {
-                            return
-                        }
+                    if (parserServices === null) {
+                        throw new Error(
+                            'TypeScript parser services not available. Rule "n/no-sync" is configured to use "ignores" option with a non-string value. This requires TypeScript parser services to be available.'
+                        )
+                    }
+
+                    const type = getTypeOfNode(node, parserServices)
+                    if (
+                        typeMatchesSpecifier(
+                            parserServices.program,
+                            ignore,
+                            type
+                        ) &&
+                        (ignore.name === undefined ||
+                            ignore.name.includes(node.name))
+                    ) {
+                        return
                     }
                 }