fix(gatsby): Remove relay compiler & use our own (#19665)

* Remove relay compiler dependency

This also reimplements fragment global scoping from Relay

* Fix latest issues

Author: freiksenet

packages/gatsby-cli/src/structured-errors/error-map.js

@@ -43,11 +43,11 @@ const errorMap = {
   },
   "85908": {
     text: context => {
-      const closetFragment = context.closestFragment
+      const closestFragment = context.closestFragment
         ? `\n\nDid you mean to use ` + `"${context.closestFragment}"?`
         : ``
 
-      return `There was an error in your GraphQL query:\n\nThe fragment "${context.fragmentName}" does not exist.${closetFragment}`
+      return `There was an error in your GraphQL query:\n\nThe fragment "${context.fragmentName}" does not exist.\n\n${context.codeFrame}${closestFragment}`
     },
     type: `GRAPHQL`,
     level: `ERROR`,
@@ -131,6 +131,21 @@ const errorMap = {
     type: `GRAPHQL`,
     level: `ERROR`,
   },
+  // Duplicate fragment
+  "85919": {
+    text: context =>
+      stripIndent(`
+      Found two different GraphQL fragments with identical name "${context.fragmentName}". Fragment names must be unique
+
+      File: ${context.leftFragment.filePath}
+      ${context.leftFragment.codeFrame}
+
+      File: ${context.rightFragment.filePath}
+      ${context.rightFragment.codeFrame}
+    `),
+    type: `GRAPHQL`,
+    level: `ERROR`,
+  },
   // Config errors
   "10123": {
     text: context =>
@@ -253,7 +268,7 @@ const errorMap = {
       [
         stripIndent(`
           Your plugins must export known APIs from their gatsby-${context.exportType}.js.
-      
+
           See https://www.gatsbyjs.org/docs/${context.exportType}-apis/ for the list of Gatsby ${context.exportType} APIs.
         `),
       ]

packages/gatsby/package.json

@@ -16,7 +16,6 @@
     "@babel/polyfill": "^7.7.0",
     "@babel/runtime": "^7.7.4",
     "@babel/traverse": "^7.7.4",
-    "@gatsbyjs/relay-compiler": "2.0.0-printer-fix.4",
     "@hapi/joi": "^15.1.1",
     "@mikaelkristiansson/domready": "^1.0.9",
     "@pieh/friendly-errors-webpack-plugin": "1.7.0-chalk-2",