[Modern] [relay-compiler] Mutation compile error. GraphQLIRPrinter: Need an InputObject type to print objects.

```
import { graphql, commitMutation } from 'react-relay';
import { ConnectionHandler } from 'relay-runtime';

const mutation = graphql`
mutation CreateConfigMutation($myConfig: ConfigInput) {
createConfig(input: { myConfig: $myConfig }) {
config {
configId
config
}
ok
}
}
`;

function addConfig(environment, configId, config) {
const variables = {
myConfig: {
configId: configId,
config: config,
},
};

commitMutation(environment, {
mutation,
variables,
onCompleted: (response, errors) => {
console.log('Response received');
},
onError: err => console.error(err),
});
}

export default { addConfig };
```

This fairly simple mutation generates an error at compile stage:

```
ERROR:
GraphQLIRPrinter: Need an InputObject type to print objects.
From: CodegenRunner.write
at invariant (/Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/node_modules/fbjs/lib/invariant.js:42:15)
at printValue (/Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1890:28)
at /Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1878:25
at Array.forEach (native)
at printArguments (/Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1877:9)
at printField (/Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1780:82)
at printSelection (/Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1787:12)
at /Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1769:13
at Array.map (native)
at printSelections (/Users/siakhnin/Documents/workspace/react-test2/node_modules/relay-compiler/bin/relay-compiler:1768:29)
error Command failed with exit code 100.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
```