Enhance pkg_name validation in feedstock_outputs.py

Update validation to check for non-empty string in pkg_name.

Author: beckermr

conda_forge_admin_requests/feedstock_outputs.py

@@ -95,10 +95,10 @@ def check(request):
         )
         r.raise_for_status()
         for pkg_name in pkgs:
-            if not isinstance(pkg_name, str):
+            if not isinstance(pkg_name, str) or len(pkg_name) == 1
                 raise ValueError(
-                    f"Value for '{feedstock}' entry must be a str (output name, or a glob), "
-                    f"but you provided {pkg_name:!r}."
+                    f"Value for '{feedstock}' entry must be a list of str (output name, or a glob), "
+                    f"but you provided {pkg_name:!r} from {pkgs:!r}."
                 )