better error when wrong type passed to import_play (ansible#36592)

fixes ansible#36576

lib/ansible/playbook/playbook_include.py

@@ -21,8 +21,8 @@
 
 import os
 
-from ansible.errors import AnsibleParserError, AnsibleError, AnsibleAssertionError
-from ansible.module_utils.six import iteritems
+from ansible.errors import AnsibleParserError, AnsibleAssertionError
+from ansible.module_utils.six import iteritems, string_types
 from ansible.parsing.splitter import split_args, parse_kv
 from ansible.parsing.yaml.objects import AnsibleBaseYAMLObject, AnsibleMapping
 from ansible.playbook.attribute import FieldAttribute
@@ -135,6 +135,8 @@ def _preprocess_import(self, ds, new_ds, k, v):
 
         if v is None:
             raise AnsibleParserError("playbook import parameter is missing", obj=ds)
+        elif not isinstance(v, string_types):
+            raise AnsibleParserError("playbook import parameter must be a string indicating a file path, got %s instead" % type(v), obj=ds)
 
         # The import_playbook line must include at least one item, which is the filename
         # to import. Anything after that should be regarded as a parameter to the import