backend graphql-core v3 adjustments (#2091)

Author: dwsutherland

src/utils/aotf.js

@@ -563,7 +563,12 @@ export function processArguments (mutation, types) {
     arg._multiple = multiple
     arg._required = required
     if (arg.defaultValue) {
-      arg._default = JSON.parse(arg.defaultValue)
+      try {
+        arg._default = JSON.parse(arg.defaultValue)
+      } catch {
+        // In Graphene 3, Enum default values changed from JSON serialised strings to plain strings
+        arg._default = arg.defaultValue
+      }
     } else {
       arg._default = getNullValue(arg.type, types)
     }