Elastic Search Synonym errors

I am new to elastic search, pretty much going by the internet articles to set it up. I am trying to create an index using a synonym file. below is my GET response for _settings call http://localhost:9200/main-products-ppe/_settings

{
        "settings": {
            "index": {
                "number_of_shards": "1",
                "provided_name": "main-products-ppe-v2",
                "creation_date": "1618410985964",
                "analysis": {
                    "filter": {
                        "lp_synonym": {
                            "type": "synonym",
                            "synonyms_path": "analysis/synonym.txt"
                        },
                        "lpl_stemmer": {
                            "type": "stemmer",
                            "language": "light_english"
                        }
                    },
                    "analyzer": {
                        "lp_analyzer": {
                            "filter": [
                                "lowercase",
                                "stop",
                                "lpl_stemmer",
                                "lp_synonym"
                            ],
                            "type": "custom",
                            "tokenizer": "standard"
                        }
                    }
                }
            }
        }
    }

I get couple of errors when trying to create index using the synonyms from the synonym file.

  1. Synonyms: can't => can not during => on Error: "Type: illegal_argument_exception Reason: "failed to build synonyms" CausedBy: "Type: parse_exception Reason: "Invalid synonym rule at line 323" CausedBy: "Type: illegal_argument_exception Reason: "term: not was completely eliminated by analyzer""""

  2. Synonyms: on sale => sale by whom => who Error: Type: illegal_argument_exception Reason: "failed to build synonyms" CausedBy: "Type: parse_exception Reason: "Invalid synonym rule at line 331" CausedBy: "Type: illegal_argument_exception Reason: "term: on sale analyzed to a token (sale) with position increment != 1 (got: 2)"""

Feels like I am missing something basic here, but not able to figure it our. If someone can explain under what circumstances these exceptions are thrown it would great. I have added additonal examples where these exception were thrown as well.