Fix chemistry mypy error (#938)

* Fix mypy error.

* Fix type error?

Author: fdmalone

qualtran/bloqs/chemistry/sparse/sparse_test.py

@@ -76,7 +76,9 @@ def keep_qrom(bloq):
         if isinstance(k, SelectSwapQROM):
             qrom_bloq = k
             break
-    return qrom_bloq.call_graph()[1][TGate()]
+    if qrom_bloq is None:
+        return 0
+    return int(qrom_bloq.call_graph()[1].get(TGate(), 0))
 
 
 @pytest.mark.slow