Argument of type 'Task<string?>' cannot be used for parameter 'value' of type 'Task<string>' in 'ConfiguredCall SubstituteExtensions.Returns<Task<string>>(Task<string> value, Task<string> returnThis, params Task<string>[] returnThese)' due to differences in the nullability of reference types.

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

Argument of type 'Task<string?>' cannot be used for parameter 'value' of type 'Task<string>' in 'ConfiguredCall SubstituteExtensions.Returns<Task<string>>(Task<string> value, Task<string> returnThis, params Task<string>[] returnThese)' due to differences in the nullability of reference types.

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

Argument of type 'Task<string?>' cannot be used for parameter 'value' of type 'Task<string>' in 'ConfiguredCall SubstituteExtensions.Returns<Task<string>>(Task<string> value, Task<string> returnThis, params Task<string>[] returnThese)' due to differences in the nullability of reference types.

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

Non-nullable property 'GitHubApiClient' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.