Could not serialize object: TypeError: cannot pickle '_thread.RLock' object

Hello I am triyin to apply two aggregate in spark datastream, with the following code

from pyspark.sql.functions import udf
from pyspark.sql.types import StringType, FloatType

@udf(returnType=FloatType())
def sent_points(x):
    words = x.split(" ")
    total = sum([negative.get(word, 0) + positive.get(word, 0) for word in words])
    return total

@udf(returnType=StringType())
def sent_type(x):
    x = sent_points(x)
    if x == 0:
        return 'NEUTRO'
    if x > 0:
        return 'POSITIVE'
    if x < 0:
        return 'NEGATIVE'

ds = df.selectExpr("CAST(value AS STRING)", "timestamp") \
.withWatermark("timestamp", "10 seconds") \
.groupBy('timestamp', 'value') \
.agg(sent_points(col('value')).alias('points')) \
.selectExpr('value', 'points', 'timestamp') \
.agg(sent_type(col('points')).alias('tipe'))

But I am going the following error:

TypeError: cannot pickle '_thread.RLock' object

This work fine if I remove the second aggregation but I need that value too.

How can I solve this, in order to get points and tipe values.

Thanks