[BUG] `str.replace is not a function` with 2 `values` CTEs

[TanguyP]

I have the following (much simplified) code:

const properties = { latitude: '3.1', longitude: '15.6' };
return await sql`
    WITH
        coords(lat, lon) AS (VALUES
            (${properties.latitude}, ${properties.longitude})
        )
        ,props(name) as (VALUES ${sql(Object.keys(properties).map(key => [key]))})
    SELECT '123'
`;

It fails with the following error:

TypeError: str.replace is not a function
    at escape (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:217:20)
    at file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:213:22
    at Array.map (<anonymous>)
    at escapeIdentifiers (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:213:13)
    at Object.select [as fn] (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:139:12)
    at Builder.build (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:71:17)
    at stringifyValue (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:109:38)
    at stringify (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/types.js:100:16)
    at build (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/connection.js:228:20)
    at execute (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/connection.js:172:7)
    at cachedError (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/query.js:170:23)
    at new Query (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/query.js:36:24)
    at sql (file:///node_modules/.pnpm/postgres@3.4.8/node_modules/postgres/src/index.js:112:11)

If I remove either one of the CTEs, it works fine. And with both CTEs it works fine when run in a Postgres client.
My scenario resembles that of #913, except I don't have any INSERT in my CTEs.