relay-compiler generates invalid Typescript for @raw_response_type + combination of conditional and non-conditional fragments

[vhfmag]

Given the code below:

export const query = graphql`
    query AppQuery($showEmail: Boolean!) @raw_response_type {
        ...AppFragment
        ...AppConditionalFragment
    }
`;

export const fragment = graphql`
    fragment AppFragment on Query {
        account {
            name
        }
    }
`;

export const conditionalFragment = graphql`
    fragment AppConditionalFragment on Query {
        account @include(if: $showEmail) {
            email
        }
    }
`;

Relay compiler generates the following types (notice the account field is listed twice):

export type AppQuery$rawResponse = {
  readonly account: {
    readonly id: string;
    readonly name: string;
  } | null | undefined;
  readonly account: {
    readonly email: string;
  } | null | undefined;
};

Which typescript interprets by using the first declaration of a given field and ignoring all others, leading to errors like:

This very reproduction can be found at https://github.com/vhfmag/relay-ts-typegen-issue-repro

Instead, relay compiler should generate something like:

export type AppQuery$rawResponse = {
  readonly account: {
    readonly id: string;
    readonly name: string;
    readonly email?: string | null | undefined;
  } | null | undefined;
};

[vhfmag]

Flow has the same issue, only in the opposite direction (it uses the last declaration instead of the first). E.g. (playground link)

export type AppQuery$rawResponse = {|
  +me: ?{|
    +firstName: ?string,
    +id: string,
  |},
  +me?: ?{|
    +lastName: ?string,
  |},
|};

function fn(val: AppQuery$rawResponse) {
  val.me.id; // Cannot get `val.me.id` because property `id` is missing in object type [1]. [prop-missing]
}