MBS-12615: Fix compactEntityJson for other-document data (#2656)

`compactEntityJson` is used to minify the relationship editor state
before putting it into sessionStorage during submission.

If you create a new entity from an autocomplete search, the returned
entity object's constructor will be from a different document (the
iframe), so we can't compare it by reference to our `Object`.  To
determine if something is a plain object, we need another way.  The
simplest is to check if the constructor function converted to a string
matches our `Object` converted to a string.

root/static/scripts/relationship-editor/components/DialogAttributes.js

@@ -16,6 +16,7 @@ import linkedEntities from '../../common/linkedEntities.mjs';
 import bracketed from '../../common/utility/bracketed.js';
 import clean from '../../common/utility/clean.js';
 import {uniqueId} from '../../common/utility/numbers.js';
+import {kebabCase} from '../../common/utility/strings.js';
 import useRangeSelectionHandler from '../hooks/useRangeSelectionHandler.js';
 import type {
   DialogAttributesStateT,
@@ -396,7 +397,11 @@ const DialogAttributes = (React.memo<PropsT>(({
 
           return (
             <div
-              className={'attribute-container ' + attribute.control}
+              className={
+                'attribute-container ' +
+                attribute.control + ' ' +
+                kebabCase(attribute.type.name)
+              }
               key={attribute.key}
             >
               {attributeElement}

root/utility/compactEntityJson.js

@@ -19,6 +19,11 @@
  *    -> [{"1": 2}, "key", "value"]
  */
 
+const functionToString: () => string =
+  // $FlowIgnore[method-unbinding]
+  Function.prototype.toString;
+const objectCtorString: string = functionToString.call(Object);
+
 function _indexValue(
   value: mixed,
   indexCache: Map<mixed, number>,
@@ -54,27 +59,35 @@ function _indexValue(
               ),
             );
           }
-        } else if (value.constructor === Object) {
-          compactValue = {};
-          for (const objectKey in value) {
-            if (hasOwnProp(value, objectKey)) {
-              const compactObjectKey = _indexValue(
-                objectKey,
-                indexCache,
-                result,
-              );
-              const compactObjectValue = _indexValue(
-                value[objectKey],
-                indexCache,
-                result,
-              );
-              compactValue[compactObjectKey] = compactObjectValue;
+        } else {
+          const prototype = Object.getPrototypeOf(value);
+          if (
+            prototype &&
+            // $FlowIgnore[prop-missing]
+            typeof prototype.constructor === 'function' &&
+            functionToString.call(prototype.constructor) === objectCtorString
+          ) {
+            compactValue = {};
+            for (const objectKey in value) {
+              if (hasOwnProp(value, objectKey)) {
+                const compactObjectKey = _indexValue(
+                  objectKey,
+                  indexCache,
+                  result,
+                );
+                const compactObjectValue = _indexValue(
+                  value[objectKey],
+                  indexCache,
+                  result,
+                );
+                compactValue[compactObjectKey] = compactObjectValue;
+              }
             }
+          } else {
+            throw new Error(
+              'Only plain objects and arrays can be converted into JSON',
+            );
           }
-        } else {
-          throw new Error(
-            'Only plain objects and arrays can be converted into JSON',
-          );
         }
       } else {
         compactValue = null;

t/selenium.mjs

@@ -665,6 +665,10 @@ const seleniumTests = [
     name: 'Series_Relationship_Editor.json5',
     login: true,
   },
+  {
+    name: 'Artist_Edit_Form.json5',
+    login: true,
+  },
   {
     name: 'Genre_Edit_Form.json5',
     login: true,