Make initializePerformance() idempotent

Author: hsubox76

packages-exp/performance-exp/src/index.ts

@@ -79,7 +79,16 @@ export function initializePerformance(
   // throw if an instance was already created.
   // It could happen if initializePerformance() is called more than once, or getPerformance() is called first.
   if (provider.isInitialized()) {
-    throw ERROR_FACTORY.create(ErrorCode.ALREADY_INITIALIZED);
+    const existingInstance = provider.getImmediate();
+    const initialSettings = provider.getOptions() as PerformanceSettings;
+    if (
+      settings?.dataCollectionEnabled === initialSettings?.dataCollectionEnabled && 
+      settings?.instrumentationEnabled === initialSettings?.instrumentationEnabled
+    ) {
+      return existingInstance;
+    } else {
+      throw ERROR_FACTORY.create(ErrorCode.ALREADY_INITIALIZED);
+    }
   }
 
   const perfInstance = provider.initialize({

packages-exp/performance-exp/src/utils/errors.ts

@@ -60,7 +60,11 @@ const ERROR_DESCRIPTION_MAP: { readonly [key in ErrorCode]: string } = {
     'Custom metric name {$customMetricName} is invalid',
   [ErrorCode.INVALID_STRING_MERGER_PARAMETER]:
     'Input for String merger is invalid, contact support team to resolve.',
-  [ErrorCode.ALREADY_INITIALIZED]: 'Performance can only be initialized once.'
+  [ErrorCode.ALREADY_INITIALIZED]: 
+  'initializePerformance() has already been called with ' +
+  'different options. To avoid this error, call initializePerformance() with the ' +
+  'same options as when it was originally called, or call getPerformance() to return the' +
+  ' already initialized instance.'
 };
 
 interface ErrorParams {