refactor(linter/plugins): debug assert that values passed via NAPI are not undefined

Author: overlookmotel

apps/oxlint/src-js/cli.ts

@@ -1,5 +1,5 @@
 import { lint } from "./bindings.js";
-import { debugAssertIsNonNull } from "./utils/asserts.ts";
+import { debugAssertIsNonNull, debugAssertIsNotUndefined } from "./utils/asserts.ts";
 
 // Lazy-loaded JS plugin-related functions.
 // The type annotations below use `typeof import("./plugins/index.ts").<fn>` so that the lazy-loaded variables
@@ -29,15 +29,20 @@ function loadPluginWrapper(
   pluginNameIsAlias: boolean,
   workspaceUri: string | null | undefined,
 ): Promise<string> {
+  // Type generated by NAPI-RS for `lint` is inaccurate.
+  // `Option::None` on Rust side becomes `null` on JS side, not `undefined`.
+  debugAssertIsNotUndefined(pluginName, "`pluginName` should not be `undefined`");
+  debugAssertIsNotUndefined(workspaceUri, "`workspaceUri` should not be `undefined`");
+
   if (loadPlugin === null) {
     // Use promises here instead of making `loadPluginWrapper` an async function,
     // to avoid a micro-tick and extra wrapper `Promise` in all later calls to `loadPluginWrapper`
     return import("./plugins/index.ts").then((mod) => {
       ({ loadPlugin, lintFile, setupRuleConfigs } = mod);
-      return loadPlugin(path, pluginName ?? null, pluginNameIsAlias, workspaceUri ?? null);
+      return loadPlugin(path, pluginName, pluginNameIsAlias, workspaceUri);
     });
   }
-  return loadPlugin(path, pluginName ?? null, pluginNameIsAlias, workspaceUri ?? null);
+  return loadPlugin(path, pluginName, pluginNameIsAlias, workspaceUri);
 }
 
 /**
@@ -78,18 +83,23 @@ function lintFileWrapper(
   globalsJSON: string,
   workspaceUri: string | null | undefined,
 ): string | null {
+  // Type generated by NAPI-RS for `lint` is inaccurate.
+  // `Option::None` on Rust side becomes `null` on JS side, not `undefined`.
+  debugAssertIsNotUndefined(buffer, "`buffer` should not be `undefined`");
+  debugAssertIsNotUndefined(workspaceUri, "`workspaceUri` should not be `undefined`");
+
   // `lintFileWrapper` is never called without `loadPluginWrapper` being called first,
   // so `lintFile` must be defined here
   debugAssertIsNonNull(lintFile);
   return lintFile(
     filePath,
     bufferId,
-    buffer ?? null,
+    buffer,
     ruleIds,
     optionsIds,
     settingsJSON,
     globalsJSON,
-    workspaceUri ?? null,
+    workspaceUri,
   );
 }
 

apps/oxlint/src-js/utils/asserts.ts

@@ -47,6 +47,36 @@ export function debugAssertIsNonNull<T>(
   }
 }
 
+/**
+ * Assert a value is not `undefined`.
+ *
+ * In release builds, is a no-op. Only does runtime checks in debug builds.
+ * Minification removes this function and all calls to it in release builds, so it has zero runtime cost.
+ *
+ * Use this for testing conditions which would indicate a bug in the code.
+ * Do NOT use this for validating user input.
+ *
+ * @param value - Value
+ * @param message - Message to include in error if `value` is `undefined`, or a function which returns the message
+ *   to include in error (optional).
+ */
+export function debugAssertIsNotUndefined<T>(
+  value: T | undefined,
+  message?: string | (() => string),
+): asserts value is T {
+  if (!DEBUG) return;
+
+  if (value === undefined) {
+    if (typeof message === "function") {
+      message = message();
+    } else if (message === undefined) {
+      message = "Expected value not to be undefined";
+    }
+
+    throw new Error(message);
+  }
+}
+
 /**
  * Debug assert that `fn` is a function.
  *