try catching stderr output

snap/snapcraft.yaml

@@ -1,7 +1,7 @@
 # yamllint disable rule:line-length
 name: charmed-postgresql # you probably want to 'snapcraft register <name>'
 base: core24 # the base snap is the execution environment for this snap
-version: '16.4' # just for humans, typically '1.2+git' or '1.3.2'
+version: '16.6' # just for humans, typically '1.2+git' or '1.3.2'
 summary: PostgreSQL in a snap.
 description: |
   PostgreSQL is a free and open-source relational database management

tests/test_smoke.py

@@ -48,10 +48,18 @@ def test_all_apps():
 
         for app, data in snapcraft["apps"].items():
             if not bool(data.get("daemon")) and app not in skip:
-                subprocess.run(
-                    f"{snapcraft['name']}.{app} {override.get(app, '--help')}".split(),
-                    check=True,
-                )
+                try:
+                    subprocess.run(
+                        f"{snapcraft['name']}.{app} {override.get(app, '--help')}".split(),
+                        check=True,
+                        capture_output=True,
+                        text=True,
+                    )
+                except subprocess.CalledProcessError as e:
+                    # Print the error and the stderr output
+                    print(f"Command failed with return code {e.returncode}")
+                    print("stderr output:")
+                    print(e.stderr)
 
 
 @pytest.mark.run(after="test_install")