fix: can not get currentContext in error handler (#1757)

Author: gxkl

__tests__/application/currentContext.js

@@ -61,4 +61,50 @@ describe('app.currentContext', () => {
 
     await request(app.callback()).get('/').expect('ok');
   });
+
+  it('should get currentContext return context in error handler when asyncLocalStorage enable', async() => {
+    const app = new Koa({ asyncLocalStorage: true });
+
+    app.use(async() => {
+      throw new Error('error message');
+    });
+
+    const handleError = new Promise((resolve, reject) => {
+      app.on('error', (err, ctx) => {
+        try {
+          assert.strictEqual(err.message, 'error message');
+          assert.strictEqual(app.currentContext, ctx);
+          resolve();
+        } catch (e) {
+          reject(e);
+        }
+      });
+    });
+
+    await request(app.callback()).get('/').expect('Internal Server Error');
+    await handleError;
+  });
+
+  it('should get currentContext return undefined in error handler when asyncLocalStorage disable', async() => {
+    const app = new Koa();
+
+    app.use(async() => {
+      throw new Error('error message');
+    });
+
+    const handleError = new Promise((resolve, reject) => {
+      app.on('error', (err, ctx) => {
+        try {
+          assert.strictEqual(err.message, 'error message');
+          assert.strictEqual(app.currentContext, undefined);
+          resolve();
+        } catch (e) {
+          reject(e);
+        }
+      });
+    });
+
+    await request(app.callback()).get('/').expect('Internal Server Error');
+    await handleError;
+  });
 });

lib/application.js

@@ -69,7 +69,6 @@ module.exports = class Application extends Emitter {
       const { AsyncLocalStorage } = require('async_hooks');
       assert(AsyncLocalStorage, 'Requires node 12.17.0 or higher to enable asyncLocalStorage');
       this.ctxStorage = new AsyncLocalStorage();
-      this.use(this.createAsyncCtxStorageMiddleware());
     }
   }
 
@@ -154,7 +153,12 @@ module.exports = class Application extends Emitter {
 
     const handleRequest = (req, res) => {
       const ctx = this.createContext(req, res);
-      return this.handleRequest(ctx, fn);
+      if (!this.ctxStorage) {
+        return this.handleRequest(ctx, fn);
+      }
+      return this.ctxStorage.run(ctx, async() => {
+        return await this.handleRequest(ctx, fn);
+      });
     };
 
     return handleRequest;