Fix sparse matrix conversion for SciPy<Real/Imaginary>Evolver (#9598) (#9600)

* Fix missing indent

* add reno

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
(cherry picked from commit e8bfdda)

Co-authored-by: Julien Gacon <gaconju@gmail.com>

Author: mergify[bot]

qiskit/algorithms/time_evolvers/classical_methods/evolve.py

@@ -109,10 +109,10 @@ def _operator_to_matrix(operator: BaseOperator | PauliSumOp):
                 "Trying dense computation",
                 type(operator),
             )
-        try:
-            op_matrix = operator.to_matrix()
-        except AttributeError as ex:
-            raise AlgorithmError(f"Unsupported operator type `{type(operator)}`.") from ex
+            try:
+                op_matrix = operator.to_matrix()
+            except AttributeError as ex:
+                raise AlgorithmError(f"Unsupported operator type `{type(operator)}`.") from ex
     return op_matrix
 
 

releasenotes/notes/fix-numpy-eigensolver-sparse-0e255d7b13b5e43b.yaml

@@ -1,6 +1,9 @@
 ---
 fixes:
   - |
-    Fixed a bug in :class:`~.minimum_eigensolvers.NumPyMinimumEigensolver` and 
-    :class:`~.eigensolvers.NumPyEigensolver` where operators that support conversion
+    Fixed a bug in the NumPy-based eigensolvers 
+    (:class:`~.minimum_eigensolvers.NumPyMinimumEigensolver` / 
+    :class:`~.eigensolvers.NumPyEigensolver`)
+    and in the SciPy-based time evolvers (:class:`.SciPyRealEvolver` / 
+    :class:`.SciPyImaginaryEvolver`), where operators that support conversion
     to sparse matrices, such as :class:`.SparsePauliOp`, were converted to dense matrices anyways.