fix: Don't emit events from failed transactions (#2806)

<!-- please provide a detailed description of the changes made in this
pull request. -->
I noticed that we emit events from the VM even when a transaction fails.
This is very difficult to write tests for because we don't display
events when a transaction fails, but I was able to verify the following
behavior BEFORE this fix:
1. Events emitted for failing transactions are stored in the block
results
2. Events emitted by `r/sys/validators` will be processed and the state
updated as normal, even if the transaction that emitted them fails

Correct me if I'm wrong, but I don't think we want to persist or take
any other actions on events sourced from failing transactions.

I'm open to suggestions on how to write tests for this, but the fix
should be self-explanatory.

<details><summary>Contributors' checklist...</summary>

- [x] Added new tests, or not needed, or not feasible
- [x] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [x] Updated the official documentation or not needed
- [x] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [x] Added references to related issues and PRs
- [x] Provided any useful hints for running manual tests
- [x] Added new benchmarks to [generated
graphs](https://gnoland.github.io/benchmarks), if any. More info
[here](https://github.com/gnolang/gno/blob/master/.benchmarks/README.md).
</details>

tm2/pkg/sdk/baseapp.go

@@ -625,11 +625,12 @@ func (app *BaseApp) runMsgs(ctx Context, msgs []Msg, mode RunTxMode) (result Res
 	ctx = ctx.WithEventLogger(NewEventLogger())
 
 	msgLogs := make([]string, 0, len(msgs))
-
 	data := make([]byte, 0, len(msgs))
-	err := error(nil)
 
-	events := []Event{}
+	var (
+		err    error
+		events = []Event{}
+	)
 
 	// NOTE: GasWanted is determined by ante handler and GasUsed by the GasMeter.
 	for i, msg := range msgs {
@@ -660,14 +661,18 @@ func (app *BaseApp) runMsgs(ctx Context, msgs []Msg, mode RunTxMode) (result Res
 				fmt.Sprintf("msg:%d,success:%v,log:%s,events:%v",
 					i, false, msgResult.Log, events))
 			err = msgResult.Error
+			events = nil
 			break
 		}
 
 		msgLogs = append(msgLogs,
 			fmt.Sprintf("msg:%d,success:%v,log:%s,events:%v",
 				i, true, msgResult.Log, events))
 	}
-	events = append(events, ctx.EventLogger().Events()...)
+
+	if err == nil {
+		events = append(events, ctx.EventLogger().Events()...)
+	}
 
 	result.Error = ABCIError(err)
 	result.Data = data