Check for undefined Value When Deleting Pages (#1902)

* Check if node is defined before reading ID property

* Revert "Check if node is defined before reading ID property"

This reverts commit c24cf3f.

* Pass node to deleteNode when deleting a SitePage node

* Fix import

packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js

@@ -6,6 +6,7 @@ const _ = require(`lodash`)
 
 const { emitter } = require(`../../redux`)
 const { boundActionCreators } = require(`../../redux/actions`)
+const { getNode } = require(`../../redux`)
 
 function transformPackageJson(json) {
   const transformDeps = deps =>
@@ -149,5 +150,7 @@ exports.onCreatePage = ({ page, boundActionCreators }) => {
 
 // Listen for DELETE_PAGE and delete page nodes.
 emitter.on(`DELETE_PAGE`, action => {
-  boundActionCreators.deleteNode(createPageId(action.payload.path))
+  const nodeId = createPageId(action.payload.path)
+  const node = getNode(nodeId)
+  boundActionCreators.deleteNode(nodeId, node)
 })