Check if the list is not empty

openmc/lib/__init__.py

@@ -20,16 +20,16 @@ def load_openmc_library():
     try:
         # Attempt to load the library from OpenMC
         import openmc
-        _filename = openmc.lib[0]
-        if os.path.isfile(_filename):
+        if openmc.lib:
+            _filename = openmc.lib[0]
             return CDLL(str(_filename))
         raise FileNotFoundError
     except (IndexError, FileNotFoundError):
         # Attempt to load the library from the installed module
         import importlib
         openmc = importlib.import_module("openmc")
-        _filename = openmc.lib[0]
-        if os.path.isfile(_filename):
+        if openmc.lib:
+            _filename = openmc.lib[0]
             warnings.warn(
                 "It seems OpenMC is being run from its source directory. "
                 "This setup is not recommended as it may lead to unexpected behavior, "