Fix more numpy / mypy typing issues (quantumlib#5669)

- Fix type complaints for np.allclose arguments
- Fix complaint about float-to-int assignment
- Fix type-complaint about optional return value

Author: pavoljuhas

cirq-core/cirq/circuits/circuit.py

@@ -2623,9 +2623,11 @@ def on_stuck(bad_op):
         on_stuck_raise=on_stuck,
     )
 
-    return protocols.apply_unitaries(
+    result = protocols.apply_unitaries(
         unitary_ops, qubits, protocols.ApplyUnitaryArgs(state, buffer, range(len(qubits)))
     )
+    assert result is not None, "apply_unitaries() should raise TypeError instead"
+    return result
 
 
 def _decompose_measurement_inversions(op: 'cirq.Operation') -> 'cirq.OP_TREE':

cirq-core/cirq/ops/kraus_channel.py

@@ -66,7 +66,7 @@ def __eq__(self, other) -> bool:
             return NotImplemented
         if self._key != other._key:
             return False
-        return np.allclose(self._kraus_ops, other._kraus_ops)
+        return np.allclose(np.asarray(self._kraus_ops), np.asarray(other._kraus_ops))
 
     def num_qubits(self) -> int:
         return self._num_qubits

cirq-core/cirq/ops/mixed_unitary_channel.py

@@ -69,7 +69,9 @@ def __eq__(self, other) -> bool:
             return False
         if not np.allclose([m[0] for m in self._mixture], [m[0] for m in other._mixture]):
             return False
-        return np.allclose([m[1] for m in self._mixture], [m[1] for m in other._mixture])
+        return np.allclose(
+            np.asarray([m[1] for m in self._mixture]), np.asarray([m[1] for m in other._mixture])
+        )
 
     def num_qubits(self) -> int:
         return self._num_qubits

cirq-core/cirq/transformers/analytical_decompositions/two_qubit_to_sqrt_iswap.py

@@ -606,11 +606,11 @@ def _decomp_3sqrt_iswap_matrices(
     if ieq1:
         if ieq2:
             # Non-canonical Weyl coordinates for the single sqrt-iSWAP
-            x1, y1, z1 = 0, np.pi / 8, -np.pi / 8
+            x1, y1, z1 = 0.0, np.pi / 8, -np.pi / 8
         else:
-            x1, y1, z1 = 0, np.pi / 8, np.pi / 8
+            x1, y1, z1 = 0.0, np.pi / 8, np.pi / 8
     else:
-        x1, y1, z1 = -np.pi / 8, np.pi / 8, 0
+        x1, y1, z1 = -np.pi / 8, np.pi / 8, 0.0
     # Non-canonical Weyl coordinates for the two sqrt-iSWAP decomposition
     x2, y2, z2 = x - x1, y - y1, z - z1