Fix: Unkwnown hashes raised exception

Problem: Many crawlers called URLs that do not exist on CRNs.

The current implementation raises an error when the hash of the VM cannot be found, which fills the logs on Sentry.

Solution: Return an HTTP Not Found status instead.

src/aleph/vm/orchestrator/views/__init__.py

@@ -65,9 +65,12 @@ async def run_code_from_path(request: web.Request) -> web.Response:
     path = request.match_info["suffix"]
     path = path if path.startswith("/") else f"/{path}"
 
-    message_ref = ItemHash(request.match_info["ref"])
-    pool: VmPool = request.app["vm_pool"]
-    return await run_code_on_request(message_ref, path, pool, request)
+    try:
+        message_ref = ItemHash(request.match_info["ref"])
+        pool: VmPool = request.app["vm_pool"]
+        return await run_code_on_request(message_ref, path, pool, request)
+    except UnknownHashError as error:
+        raise HTTPNotFound(reason="Invalid message reference") from error
 
 
 async def run_code_from_hostname(request: web.Request) -> web.Response:
@@ -100,6 +103,8 @@ async def run_code_from_hostname(request: web.Request) -> web.Response:
                 logger.debug(f"Using DNS TXT record to obtain '{message_ref}'")
             except aiodns.error.DNSError as error:
                 raise HTTPNotFound(reason="Invalid message reference") from error
+            except UnknownHashError as error:
+                raise HTTPNotFound(reason="Invalid message reference") from error
 
     pool = request.app["vm_pool"]
     return await run_code_on_request(message_ref, path, pool, request)