Typescript generation error "Cannot read property 'getType' of undefined"

Getting a confusing error when generating typescript files, as it is a bit in the bowels I'm not sure if I'm messing something up or if I'm using bad options. I can provide the schema if interested.

apollo codegen:generate --addTypename --target typescript graphql

√ Loading Apollo config
√ Scanning for GraphQL queries (458 found)
× Generating query files with 'typescript' target
→ Cannot read property 'getType' of undefined
TypeError: Cannot read property 'getType' of undefined
at Object.NamedType (C:/Users//AppData/Roaming/npm/node_modules/apollo/node_modules/graphql/validation/rules/KnownTypeNames.js:64:25)

Start by reproducing the reported `apollo codegen:generate --addTypename --target typescript graphql` command with the relevant schema and queries. Inspect the TypeScript generation path and the reported `KnownTypeNames.js` failure at line 64, then confirm that generation completes without the `getType` error for the supplied case.

Written by the indexing model from the issue text.