Return 404 if requested ressource does not exist.

app/api/views.py

-from flask import jsonify
+from flask import abort, jsonify
 from flask_login import current_user, login_required
 from . import api
 
@@ -20,8 +20,7 @@ def corpora():
 def corpus(corpus_id):
     corpus = current_user.corpora.filter_by(id=corpus_id).first()
     if not corpus:
-        ''' This should return 404 '''
-        return jsonify(None)
+        return abort(404)
     return jsonify({'id': corpus.id,
                     'creation_date': corpus.creation_date,
                     'description': corpus.description,
@@ -36,7 +35,8 @@ def jobs():
         jobs.append({'id': job.id,
                      'creation_date': job.creation_date.timestamp(),
                      'description': job.description,
-                     'end_date': job.end_date.timestamp() if job.end_date else None,
+                     'end_date': (job.end_date.timestamp() if job.end_date else
+                                  None),
                      'mem_mb': job.mem_mb,
                      'n_cores': job.n_cores,
                      'service': job.service,
@@ -52,12 +52,12 @@ def jobs():
 def job(job_id):
     job = current_user.jobs.filter_by(id=job_id).first()
     if not job:
-        ''' This should return 404 '''
-        return jsonify(None)
+        return abort(404)
     return jsonify({'id': job.id,
                     'creation_date': job.creation_date.timestamp(),
                     'description': job.description,
-                    'end_date': job.end_date.timestamp() if job.end_date else None,
+                    'end_date': (job.end_date.timestamp() if job.end_date else
+                                 None),
                     'mem_mb': job.mem_mb,
                     'n_cores': job.n_cores,
                     'service': job.service,