feat: Safeguard for name prop in transaction

Author: HazAT

packages/apm/src/hubextensions.ts

@@ -1,5 +1,6 @@
 import { getMainCarrier, Hub } from '@sentry/hub';
 import { SpanContext, TransactionContext } from '@sentry/types';
+import { logger } from '@sentry/utils';
 
 import { Span } from './span';
 import { Transaction } from './transaction';
@@ -48,8 +49,16 @@ function startSpan(context: SpanContext | TransactionContext): Transaction | Spa
     }
   }
 
-  // We are dealing with a Transaction
+  // This is our safeguard so people always get a Transaction in return.
+  // We set `_isTransaction: true` in {@link Sentry.startTransaction} to have a runtime check
+  // if the user really wanted to create a Transaction.
+  if ((context as TransactionContext)._isTransaction && !(context as TransactionContext).name) {
+    logger.warn('You are trying to start a Transaction but forgot to provide a `name` property.');
+    logger.warn('Will fall back to <unlabeled transaction>, use `transaction.setName()` to change it.');
+  }
+
   if ((newSpanContext as TransactionContext).name) {
+    // We are dealing with a Transaction
     const transaction = new Transaction(newSpanContext as TransactionContext, hub);
 
     // We only roll the dice on sampling for root spans of transactions because all child spans inherit this state

packages/minimal/src/index.ts

@@ -175,5 +175,8 @@ export function _callOnClient(method: string, ...args: any[]): void {
  * a transaction it will be sent to Sentry.
  */
 export function startTransaction(transactionContext: TransactionContext): Transaction {
-  return callOnHub<Transaction>('startSpan', transactionContext);
+  return callOnHub<Transaction>('startSpan', {
+    ...transactionContext,
+    _isTransaction: true,
+  });
 }

packages/types/src/transaction.ts

@@ -12,6 +12,13 @@ export interface TransactionContext extends SpanContext {
    * transaction after a given "idle time" and we don't want this "idle time" to be part of the transaction.
    */
   trimEnd?: boolean;
+
+  /**
+   * This flag is internally used by {@link Sentry.startTransaction} and set there to determine this is really a
+   * Transaction. Since there is no type safety in JS we set it in the top level function to true to check later
+   * if the user really wanted to create a Transaction and we can log a warning if they forgot to set the name property.
+   */
+  _isTransaction?: boolean;
 }
 
 /**