Fix typo adding non-gates to _collect_1q_runs() output

qiskit/dagcircuit/dagcircuit.py

@@ -1441,10 +1441,11 @@ def _collect_1q_runs(self):
                 while len(s) == 1 and \
                         s[0].type == "op" and \
                         len(s[0].qargs) == 1 and \
-                        len(s[0].cargs) == 0 and \
+                        not s[0].cargs and \
                         s[0].condition is None and \
+                        s[0] not in nodes_seen and \
                         not s[0].op.is_parameterized() and \
-                        isinstance(node.op, Gate):
+                        isinstance(s[0].op, Gate):
                     group.append(s[0])
                     nodes_seen.add(s[0])
                     s = self._multi_graph.successors(s[0]._node_id)

releasenotes/notes/fix-invalid-ops-collect-runs-b9fd2f2e85136834.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Fixed an issue introduced in 0.16.2 that would cause errors when running
+    :func:`~qiskit.compiler.transpile` on a circuit with a series of 1 qubit
+    gates and a non-gate instruction that only operates on a qubit (e.g.
+    :class:`~qiskit.circuit.Reset`). Fixes
+    `#5736 <https://github.com/Qiskit/qiskit-terra/issues/5736>`__

test/python/dagcircuit/test_dagcircuit.py

@@ -734,6 +734,21 @@ def test_dag_collect_1q_runs(self):
             else:
                 self.fail('Unknown run encountered')
 
+    def test_dag_no_reset_in_collect_1q_runs(self):
+        """Test a run does not include a reset instruction."""
+        dag = DAGCircuit()
+        qreg = QuantumRegister(1, 'qr')
+        creg = ClassicalRegister(1, 'cr')
+        dag.add_qreg(qreg)
+        dag.add_creg(creg)
+        dag.apply_operation_back(U1Gate(3.14), [qreg[0]])
+        dag.apply_operation_back(HGate(), [qreg[0]])
+        dag.apply_operation_back(Reset(), [qreg[0]])
+        dag.apply_operation_back(Measure(), [qreg[0]], [creg[0]])
+        runs = dag._collect_1q_runs()
+        self.assertEqual([[x.name for x in run] for run in runs],
+                         [['u1', 'h']])
+
     def test_dag_collect_1q_runs_start_with_conditional(self):
         """Test collect 1q runs with a conditional at the start of the run."""
         h_gate = HGate()