Add JobNotFoundError and handlers to Flask to cleanup some methods

lib/render_queue.py

@@ -16,6 +16,12 @@ JSON_FILE = 'server_state.json'
 #todo: move history to sqlite db
 
 
+class JobNotFoundError(Exception):
+    def __init__(self, job_id, *args):
+        super().__init__(args)
+        self.job_id = job_id
+
+
 class RenderQueue:
     job_queue = []
     render_clients = []
@@ -61,8 +67,10 @@ class RenderQueue:
         return found_jobs
 
     @classmethod
-    def job_with_id(cls, job_id):
+    def job_with_id(cls, job_id, none_ok=False):
         found_job = next((x for x in cls.job_queue if x.id == job_id), None)
+        if not found_job and not none_ok:
+            raise JobNotFoundError(job_id)
         return found_job
 
     @classmethod