* handle another edge case

jax/_src/scipy/sparse/linalg.py

@@ -289,17 +289,17 @@ def cg(A, b, x0=None, *, tol=1e-5, atol=0.0, maxiter=None, M=None,
     # real-valued positive-definite linear operators are symmetric.
     def real_valued(x):
       return not issubclass(jnp.result_type(x).type, np.complexfloating)
-    if callable(A) and x0 is not None:
-      # we use output dtype as the proxy for dtype.
-      symmetric = all(map(real_valued,
-                          tree_leaves(jax.eval_shape(A, x0))))
-    else:
-      try:
-        # Prefer to use the dtype of the operator, if available.
-        symmetric = real_valued(A)
-      except AttributeError:
-        # fall back to the RHS.
-        symmetric = all(map(real_valued, tree_leaves(b)))
+
+    try:
+      # Prefer to use the dtype of the operator, if available.
+      if callable(A) and x0 is not None:
+        symmetric = all(map(real_valued,
+                            tree_leaves(jax.eval_shape(A, x0))))
+      else:
+          symmetric = real_valued(A)
+    except TypeError:
+      # fall back to the RHS.
+      symmetric = all(map(real_valued, tree_leaves(b)))
   return _isolve(_cg_solve,
                  A=A, b=b, x0=x0, tol=tol, atol=atol,
                  maxiter=maxiter, M=M, symmetric=symmetric)