ClassNotFoundException on keyword

I have a keyword I use to log in to a website. It used to work just fine for months, today it is not working.

This is the error:

SLF4J: The requested version 1.7.16 by your slf4j binding is not compatible with [1.6]
SLF4J: See SLF4J Error Codes for further details.
2019-12-30 11:36:28.135 INFO c.k.katalon.core.main.TestCaseExecutor - --------------------
2019-12-30 11:36:28.142 INFO c.k.katalon.core.main.TestCaseExecutor - START Test Cases/Scenarios/Make a new Scenario
2019-12-30 11:36:28.877 INFO c.k.katalon.core.main.TestCaseExecutor - (Default) DL1 = **********************************************************************************************
2019-12-30 11:36:29.560 DEBUG testcase.Make a new Scenario - 1: package1.FiveCastLogin.Login()
2019-12-30 11:36:29.603 ERROR k.k.c.m.CustomKeywordDelegatingMetaClass - :x: package1.FiveCastLogin
2019-12-30 11:36:29.608 ERROR c.k.katalon.core.main.TestCaseExecutor - :x: Test Cases/Scenarios/Make a new Scenario FAILED.
Reason:
java.lang.ClassNotFoundException: package1.FiveCastLogin
at com.kms.katalon.core.main.CustomKeywordDelegatingMetaClass.getCustomKeywordClassAndSetMetaClass(CustomKeywordDelegatingMetaClass.java:100)
at com.kms.katalon.core.main.CustomKeywordDelegatingMetaClass.invokeStaticMethod(CustomKeywordDelegatingMetaClass.java:45)
at Make a new Scenario.run(Make a new Scenario:17)
at com.kms.katalon.core.main.ScriptEngine.run(ScriptEngine.java:194)
at com.kms.katalon.core.main.ScriptEngine.runScriptAsRawText(ScriptEngine.java:119)
at com.kms.katalon.core.main.TestCaseExecutor.runScript(TestCaseExecutor.java:337)
at com.kms.katalon.core.main.TestCaseExecutor.doExecute(TestCaseExecutor.java:328)
at com.kms.katalon.core.main.TestCaseExecutor.processExecutionPhase(TestCaseExecutor.java:307)
at com.kms.katalon.core.main.TestCaseExecutor.accessMainPhase(TestCaseExecutor.java:299)
at com.kms.katalon.core.main.TestCaseExecutor.execute(TestCaseExecutor.java:233)
at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:114)
at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:105)
at com.kms.katalon.core.main.TestCaseMain$runTestCase$0.call(Unknown Source)
at TempTestCase1577727346348.run(TempTestCase1577727346348.groovy:21)

2019-12-30 11:36:29.636 INFO c.k.katalon.core.main.TestCaseExecutor - END Test Cases/Scenarios/Make a new Scenario

i have stripped out all my lines in my test case so now it just looks like this:

import static com.kms.katalon.core.checkpoint.CheckpointFactory.findCheckpoint
import static com.kms.katalon.core.testcase.TestCaseFactory.findTestCase
import static com.kms.katalon.core.testdata.TestDataFactory.findTestData
import static com.kms.katalon.core.testobject.ObjectRepository.findTestObject
import com.kms.katalon.core.checkpoint.Checkpoint as Checkpoint
import com.kms.katalon.core.cucumber.keyword.CucumberBuiltinKeywords as CucumberKW
import com.kms.katalon.core.mobile.keyword.MobileBuiltInKeywords as Mobile
import com.kms.katalon.core.model.FailureHandling as FailureHandling
import com.kms.katalon.core.testcase.TestCase as TestCase
import com.kms.katalon.core.testdata.TestData as TestData
import com.kms.katalon.core.testobject.TestObject as TestObject
import com.kms.katalon.core.webservice.keyword.WSBuiltInKeywords as WS
import com.kms.katalon.core.webui.keyword.WebUiBuiltInKeywords as WebUI
import internal.GlobalVariable as GlobalVariable

‘Login’
CustomKeywords.‘package1.FiveCastLogin.Login’()