clone json obj in relay flight client host config parser (facebook#20465

)

When `parseModel` suspends because of missing dependencies, it will exit and retry to parse later. However, in the relay implementation, the model is an object that we modify in place when we parse it, so when we we retry, part of the model might be parsed already into React elements, which will error because the parsing code expect a Flight model. This diff clones instead of mutating the original model, which fixes this error.

packages/react-server-dom-relay/src/ReactFlightDOMRelayClientHostConfig.js

@@ -36,18 +36,25 @@ function parseModelRecursively(response: Response, parentObj, value) {
   }
   if (typeof value === 'object' && value !== null) {
     if (Array.isArray(value)) {
+      const parsedValue = [];
       for (let i = 0; i < value.length; i++) {
-        (value: any)[i] = parseModelRecursively(response, value, value[i]);
+        (parsedValue: any)[i] = parseModelRecursively(
+          response,
+          value,
+          value[i],
+        );
       }
-      return parseModelTuple(response, value);
+      return parseModelTuple(response, parsedValue);
     } else {
+      const parsedValue = {};
       for (const innerKey in value) {
-        (value: any)[innerKey] = parseModelRecursively(
+        (parsedValue: any)[innerKey] = parseModelRecursively(
           response,
           value,
           value[innerKey],
         );
       }
+      return parsedValue;
     }
   }
   return value;