fix: prefix graphql type names with underscore if it starts with numb…

…er (#10007)

if object or array is under field that starts with number it will cause graphql to fail with:
```
Error: Names must match /^[_a-zA-Z][_a-zA-Z0-9]*$/ but "6E0F4D382F504Ac5837DF8B7C8618485_2" does not.
```

to workaround it - prefix type name with `_` if it starts with number

fixes #9950

/cc @phonoman

packages/gatsby/src/schema/__tests__/infer-graphql-type-test.js

@@ -87,6 +87,9 @@ describe(`GraphQL type inferance`, () => {
       "with-hyphen": 2,
       "with resolver": `1012-11-01`,
       123: 42,
+      456: {
+        testingTypeNameCreation: true,
+      },
       aBoolean: true,
       externalUrl: `https://example.com/awesome.jpg`,
       domain: `pizza.com`,
@@ -242,6 +245,9 @@ describe(`GraphQL type inferance`, () => {
         with_hyphen
         with_resolver(formatString:"DD.MM.YYYY")
         _123
+        _456 {
+          testingTypeNameCreation
+        }
       `
     )
 
@@ -254,6 +260,7 @@ describe(`GraphQL type inferance`, () => {
     expect(result.data.listNode[0].with_resolver).toEqual(`01.11.1012`)
     expect(result.data.listNode[0]._123).toEqual(42)
     expect(result.data.listNode[1]._123).toEqual(24)
+    expect(result.data.listNode[0]._456).toEqual(nodes[0][`456`])
   })
 
   describe(`Handles dates`, () => {

packages/gatsby/src/schema/create-type-name.js

@@ -2,8 +2,18 @@ const _ = require(`lodash`)
 
 const seenNames = new Map()
 
+const typeNameRestriction = /^[_a-zA-Z][_a-zA-Z0-9]*$/
+
 module.exports = function createTypeName(name) {
-  const cameledName = _.camelCase(name)
+  let cameledName = _.camelCase(name)
+
+  // camelCasing will ensure that name is build from just alphanumeric
+  // characters, but we still need to ensure that type name
+  // doesn't start with number (graphql resitriction)
+  if (!cameledName.match(typeNameRestriction)) {
+    cameledName = `_` + cameledName
+  }
+
   if (seenNames.has(cameledName)) {
     seenNames.set(cameledName, seenNames.get(cameledName) + 1)
     return `${cameledName}_${seenNames.get(cameledName)}`