Fix exception on unknown label when creating a VM

get_label() already raises QubesLabelNotFoundError, do not convert it
to a generic one.

Author: marmarek

qubes/api/admin.py

@@ -1216,10 +1216,8 @@ async def _vm_create(
                 self.enforce(not untrusted_value.isdigit())
                 allowed_chars = string.ascii_letters + string.digits + "-_."
                 self.enforce(all(c in allowed_chars for c in untrusted_value))
-                try:
-                    kwargs["label"] = self.app.get_label(untrusted_value)
-                except KeyError:
-                    raise qubes.exc.QubesValueError
+                # this may raise QubesLabelNotFoundError
+                kwargs["label"] = self.app.get_label(untrusted_value)
 
             elif untrusted_key == "pool" and allow_pool:
                 if pool is not None: