[SIEM] GraphQL type generation fails to generate types

[spong]

With the latest from master, running node scripts/generate_types_from_graphql.js from ${KIBANA_HOME}/x-pack/legacy/plugins/siem to generate the graphql types fails with the following error:

  ✖ Parse configuration
    → Cannot convert undefined or null to object
    Generate outputs
Cannot convert undefined or null to object
(node:31823) UnhandledPromiseRejectionWarning: TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at normalize (/Users/garrettspong/dev/kibana/node_modules/graphql-code-generator/src/codegen.ts:84:33)
    at Task.task (/Users/garrettspong/dev/kibana/node_modules/graphql-code-generator/src/codegen.ts:150:17)
    at Promise.resolve.then.then.skipped (/Users/garrettspong/dev/kibana/node_modules/graphql-code-generator/node_modules/listr/lib/task.js:167:30)
    at process._tickCallback (internal/process/next_tick.js:68:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:745:11)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:743:3)
(node:31823) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:31823) [DEP0018] Depre

This appears to the be results of the recent upgrade of graphql-code-generator from "^0.13.0" to "^0.18.2", which introduces a familiar breaking change from a few months ago. Yay semver!

[elasticmachine]

Pinging @elastic/siem