fix!: force genOrBroadcastFn even when max-msgs != 0

If cli tx withdraw-all-rewards sends empty tx, the tx would be
rejected by validators because it has no msgs. However, the cli sends
empty tx only if one sets `--max-msgs=0` which means it does not split
the msgs. When you set `max-msgs` with any positive number, the cli
does not send any tx, which may confuse you because you cannot get the
feedback indicating the address has no delegations.
This patch addresses the problem, by forcing genOrBroadcastFn when the
number of total msgs generated is zero. It will provide the same user
experience with any `max-msgs`.

x/distribution/client/cli/tx.go

@@ -52,13 +52,12 @@ func newSplitAndApply(
 	genOrBroadcastFn newGenerateOrBroadcastFunc, clientCtx client.Context,
 	fs *pflag.FlagSet, msgs []sdk.Msg, chunkSize int,
 ) error {
-
-	if chunkSize == 0 {
+	totalMessages := len(msgs)
+	if chunkSize == 0 || totalMessages == 0 {
 		return genOrBroadcastFn(clientCtx, fs, msgs...)
 	}
 
 	// split messages into slices of length chunkSize
-	totalMessages := len(msgs)
 	for i := 0; i < len(msgs); i += chunkSize {
 
 		sliceEnd := i + chunkSize

x/distribution/client/cli/tx_test.go

@@ -21,8 +21,19 @@ import (
 func Test_splitAndCall_NoMessages(t *testing.T) {
 	clientCtx := client.Context{}
 
-	err := newSplitAndApply(nil, clientCtx, nil, nil, 10)
-	assert.NoError(t, err, "")
+	// empty tx will always trigger genOrBroadcastFn
+	maxMsgsCases := []int{0, 1, 10}
+	calledCounter := 0
+	for _, maxMsgs := range maxMsgsCases {
+		err := newSplitAndApply(
+			func(clientCtx client.Context, fs *pflag.FlagSet, msgs ...sdk.Msg) error {
+				// dummy genOrBroadcastFn called once for each case
+				calledCounter++
+				return nil
+			}, clientCtx, nil, nil, maxMsgs)
+		assert.NoError(t, err, "")
+	}
+	assert.Equal(t, calledCounter, len(maxMsgsCases))
 }
 
 func Test_splitAndCall_Splitting(t *testing.T) {