fix(babel-preset-gatsby): Show a helpful error when used in the wrong…

… environment (#11555)

packages/babel-preset-gatsby/src/index.js

@@ -5,10 +5,21 @@ const resolve = m => require.resolve(m)
 const loadCachedConfig = () => {
   let pluginBabelConfig = {}
   if (process.env.NODE_ENV !== `test`) {
-    pluginBabelConfig = require(path.join(
-      process.cwd(),
-      `./.cache/babelState.json`
-    ))
+    try {
+      pluginBabelConfig = require(path.join(
+        process.cwd(),
+        `./.cache/babelState.json`
+      ))
+    } catch (err) {
+      if (err.message.includes(`Cannot find module`)) {
+        // This probably is being used outside of the Gatsby CLI.
+        throw Error(
+          `\`babel-preset-gatsby\` has been loaded, which consumes config generated by the Gatsby CLI. Set \`NODE_ENV=test\` to bypass, or run \`gatsby build\` first.`
+        )
+      } else {
+        throw err
+      }
+    }
   }
   return pluginBabelConfig
 }