Don't exit on config file load error

Author: webpro

packages/docs/src/content/docs/reference/known-issues.md

@@ -8,12 +8,12 @@ See [handling issues][1] to learn more about dealing with lint issues.
 
 ## Exceptions from config files
 
-An exception may be thrown when a Knip plugin loads a JavaScript or TypeScript
-configuration file such as `webpack.config.js` or `vite.config.ts`:
+Knip plugins may fail to load a JavaScript or TypeScript configuration file
+such as `webpack.config.js` or `vite.config.ts`:
 
 ```sh
 $ knip
-Error loading .../vite.config.ts
+ERROR: Error loading vite.config.ts
 ```
 
 Knip may load such files differently, in a different environment, with missing
@@ -27,6 +27,7 @@ Potential workarounds:
   - Use a helper package like [dotenvx][3]
   - `KEY=VAL knip`
   - `node --env-file .env $(which knip)`
+- Run the build script to generate required files.
 - Disable loading the file by overriding the default `config` for that plugin.
   - Example: `vite: { config: [] }`
   - In a monorepo, be more specific like so:

packages/knip/fixtures/plugin-config-load-error/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "@fixtures/plugin-config-load-error",
+  "main": "./src/index.ts",
+  "scripts": {
+    "build": "vite build"
+  },
+  "devDependencies": {
+    "vite": "*"
+  }
+}

packages/knip/fixtures/plugin-config-load-error/src/index.ts

@@ -0,0 +1 @@
+export const greet = (name: string) => `hello ${name}`;

packages/knip/fixtures/plugin-config-load-error/vite.config.ts

@@ -0,0 +1,3 @@
+import './missing-bootstrap-output.js';
+
+export default { build: { outDir: 'dist' } };

packages/knip/src/WorkspaceWorker.ts

@@ -40,8 +40,10 @@ import {
 import { getPackageNameFromSpecifier } from './util/modules.ts';
 import { getKeysByValue } from './util/object.ts';
 import { timerify } from './util/Performance.ts';
-import { basename, dirname, isInternal, join } from './util/path.ts';
+import { basename, dirname, isInternal, join, toRelative } from './util/path.ts';
 import { extractPatternExtensions } from './util/pattern-extensions.ts';
+import { formatCauseMessage } from './util/errors.ts';
+import { logError } from './util/log.ts';
 import { loadConfigForPlugin } from './util/plugin.ts';
 import { ELLIPSIS } from './util/string.ts';
 
@@ -428,14 +430,24 @@ export class WorkspaceWorker {
           if (!cache.resolveConfig) {
             const isLoad =
               typeof plugin.isLoadConfig === 'function' ? plugin.isLoadConfig(resolveOpts, this.dependencies) : true;
-            const localConfig = isLoad && (await loadConfigForPlugin(configFilePath, plugin, resolveOpts, pluginName));
-            if (localConfig) {
-              const inputs = await plugin.resolveConfig(localConfig, resolveOpts);
-              if (plugin.isFilterTransitiveDependencies && !isManifest) {
-                this.filterTransitiveDependencies(inputs, configFilePath);
+            if (isLoad) {
+              try {
+                const localConfig = await loadConfigForPlugin(configFilePath, plugin, resolveOpts, pluginName);
+                if (localConfig) {
+                  const inputs = await plugin.resolveConfig(localConfig, resolveOpts);
+                  if (plugin.isFilterTransitiveDependencies && !isManifest) {
+                    this.filterTransitiveDependencies(inputs, configFilePath);
+                  }
+                  for (const input of inputs) addInput(input, configFilePath);
+                  cache.resolveConfig = inputs;
+                }
+              } catch (error) {
+                if (!(error instanceof Error)) throw error;
+                const relPath = toRelative(configFilePath, this.options.cwd);
+                const cause = formatCauseMessage(error, this.options.cwd);
+                logError(`Error loading ${relPath} (${cause})`);
+                logError('Please fix or visit https://knip.dev/reference/known-issues');
               }
-              for (const input of inputs) addInput(input, configFilePath);
-              cache.resolveConfig = inputs;
             }
           }
         }

packages/knip/src/util/errors.ts

@@ -22,6 +22,12 @@ export const isModuleNotFoundError = (error: Error): boolean => 'code' in error
 
 export const isLoaderError = (error: Error): error is LoaderError => error instanceof LoaderError;
 
+export const formatCauseMessage = (error: Error, cwd: string) => {
+  let root: Error = error;
+  while (root.cause instanceof Error) root = root.cause;
+  return root.message.split('\n', 1)[0].replace(`${cwd}/`, '');
+};
+
 export const getKnownErrors = (error: Error) => {
   if (isZodErrorLike(error))
     return [...error.issues].map(error => {

packages/knip/test/plugin-config-load-error.test.ts

@@ -0,0 +1,27 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { main } from '../src/index.ts';
+import { createOptions } from './helpers/create-options.ts';
+import { exec } from './helpers/exec.ts';
+import { resolve } from './helpers/resolve.ts';
+
+const cwd = resolve('fixtures/plugin-config-load-error');
+
+test('Plugin config that throws on load should not be fatal', async () => {
+  const options = await createOptions({ cwd });
+  await assert.doesNotReject(main(options));
+  const { counters } = await main(options);
+  assert.equal(counters.processed, 2);
+});
+
+test('Plugin config that throws on load exits non-zero via CLI', () => {
+  const result = exec('knip --no-progress', { cwd });
+  assert.match(result.stderr, /^ERROR: Error loading vite\.config\.ts /m);
+  assert.equal(result.status, 1);
+});
+
+test('Plugin config that throws on load exits zero with --no-exit-code', () => {
+  const result = exec('knip --no-progress --no-exit-code', { cwd });
+  assert.match(result.stderr, /^ERROR: Error loading vite\.config\.ts /m);
+  assert.equal(result.status, 0);
+});