fix: skip tables with no patch type

Author: mlipscombe

package.json

@@ -1,6 +1,6 @@
 {
   "name": "postgraphile-plugin-nested-mutations",
-  "version": "1.0.0-alpha.21",
+  "version": "1.0.0-alpha.22",
   "description": "Nested mutations plugin for PostGraphile",
   "main": "index.js",
   "repository": {

src/PostgraphileNestedUpdatersPlugin.js

@@ -208,6 +208,10 @@ module.exports = function PostGraphileNestedUpdatersPlugin(
               inflection.patchType(ForeignTableType.name),
             );
 
+            if (!ForeignTablePatch) {
+              return;
+            }
+
             const patchType = newWithHooks(
               GraphQLInputObjectType,
               {