fix(response): set content-type when unable to stream file

Safari will force download the stream error in response when `X-Content-Type: nosniff`
header is set. To avoid this, we need to set explicit content type header

Author: thetutlage

src/Response/index.ts

@@ -291,6 +291,7 @@ export class Response extends Macroable implements ResponseContract {
         finished = true
         destroy(body)
 
+        this.type('text')
         if (typeof (errorCallback) === 'function') {
           this.endResponse(...errorCallback(error))
         } else {
@@ -385,6 +386,8 @@ export class Response extends Macroable implements ResponseContract {
        */
       return this.streamBody(createReadStream(filePath), errorCallback)
     } catch (error) {
+      this.type('text')
+
       if (typeof (errorCallback) === 'function') {
         this.endResponse(...errorCallback(error))
       } else {

test/response.spec.ts

@@ -551,8 +551,9 @@ test.group('Response', (group) => {
       response.finish()
     })
 
-    const { text } = await supertest(server).get('/').expect(404)
+    const { text, header } = await supertest(server).get('/').expect(404)
     assert.equal(text, 'File not found')
+    assert.equal(header['content-type'], 'text/plain; charset=utf-8')
   })
 
   test('return custom message and status when file is missing', async (assert) => {