fix: improve fetch-schema logging and platform support (#6191)

* fix: improve fetch-schema logging and platform support

* don't use async/await because linter doesn't like it

scripts/fetch-schema.js

 /* eslint-env node */
 
 require('dotenv').config({ path: '.env.production' })
-
-const { exec } = require('child_process')
+const child_process = require('child_process')
+const fs = require('fs/promises')
+const { promisify } = require('util')
 const dataConfig = require('../graphql.config')
 const thegraphConfig = require('../graphql_thegraph.config')
 
+const exec = promisify(child_process.exec)
+
 function fetchSchema(url, outputFile) {
-  exec(
-    `get-graphql-schema --h Origin=https://app.uniswap.org ${url} | tee ${outputFile}.temp`,
-    (error, stdout, stderr) => {
-      if (error || stderr) {
-        console.log(`Failed to fetch schema from ${url}`)
-      } else if (stdout) {
-        exec(`mv ${outputFile}.temp ${outputFile}`)
+  exec(`npx get-graphql-schema --h Origin=https://app.uniswap.org ${url}`)
+    .then(({ stderr, stdout }) => {
+      if (stderr) {
+        throw new Error(stderr)
+      } else {
+        fs.writeFile(outputFile, stdout)
       }
-    }
-  )
+    })
+    .catch((err) => {
+      console.error(err)
+      console.error(`Failed to fetch schema from ${url}`)
+    })
 }
 
 fetchSchema(process.env.THE_GRAPH_SCHEMA_ENDPOINT, thegraphConfig.schema)