NullPointerException for MediaType.getSchema()

I’m facing a NullPointerException issue.

The command that I ran was: ./cats.jar --contract=openapi.yaml --server=https://subdomain.domain-name --paths=/v1/endpoint --headers=headers.yaml

Result Info

[********* ][*****] ● note     Proxy configuration to be used: DIRECT
[********* ][*****] ▶ start    Starting CATS, version 6.0.4, build-time 2021-07-23T06:05:54.116 UTC
[********* ][*****] ● note     Processing configuration...
[********* ][*****] ℹ info     No security custom Fuzzer file. SecurityFuzzer will be skipped!
[********* ][*****] ℹ info     No custom Fuzzer file. CustomFuzzer will be skipped!
[********* ][*****] ℹ info     No reference data file was supplied! Payloads supplied by Fuzzers will remain unchanged!
[********* ][*****] ▶ start    skipXXXForPath supplied arguments: []. Matching with registered fuzzers...
[********* ][*****] ☑ complete skipXXXForPath list after matching with registered fuzzers: []
[********* ][*****] ✖ error    Something went wrong while running CATS!
java.lang.NullPointerException: Cannot invoke "io.swagger.v3.oas.models.media.MediaType.getSchema()" because the return value of "io.swagger.v3.oas.models.media.Content.get(Object)" is null
	at com.endava.cats.CatsMain.addToSchemas(CatsMain.java:123)
	at com.endava.cats.CatsMain.lambda$getSchemas$0(CatsMain.java:111)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:723)
	at com.endava.cats.CatsMain.getSchemas(CatsMain.java:111)
	at com.endava.cats.CatsMain.fuzzPath(CatsMain.java:355)
	at com.endava.cats.CatsMain.startFuzzing(CatsMain.java:175)
	at com.endava.cats.CatsMain.doLogic(CatsMain.java:166)
	at com.endava.cats.CatsMain.run(CatsMain.java:144)
	at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:791)
	at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:775)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:345)
	at com.endava.cats.CatsMain.main(CatsMain.java:102)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
	at org.springframework.boot.loader.Launcher.launch(Launcher.java:108)
	at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
	at org.springframework.boot.loader.PropertiesLauncher.main(PropertiesLauncher.java:467)

How can I fix this issue?