'reload' action should be allowed even where there's no match

If the command template doesn't have any placeholder expressions.

    : | fzf --bind 'space:reload:seq 10'

src/terminal.go

@@ -1237,7 +1237,7 @@ func parsePlaceholder(match string) (bool, string, placeholderFlags) {
 	return false, matchWithoutFlags, flags
 }
 
-func hasPreviewFlags(template string) (plus bool, query bool) {
+func hasPreviewFlags(template string) (slot bool, plus bool, query bool) {
 	for _, match := range placeholder.FindAllString(template, -1) {
 		_, _, flags := parsePlaceholder(match)
 		if flags.plus {
@@ -1246,6 +1246,7 @@ func hasPreviewFlags(template string) (plus bool, query bool) {
 		if flags.query {
 			query = true
 		}
+		slot = true
 	}
 	return
 }
@@ -1409,7 +1410,7 @@ func (t *Terminal) currentItem() *Item {
 
 func (t *Terminal) buildPlusList(template string, forcePlus bool) (bool, []*Item) {
 	current := t.currentItem()
-	plus, query := hasPreviewFlags(template)
+	_, plus, query := hasPreviewFlags(template)
 	if !(query && len(t.input) > 0 || (forcePlus || plus) && len(t.selected) > 0) {
 		return current != nil, []*Item{current, current}
 	}
@@ -2045,11 +2046,12 @@ func (t *Terminal) Loop() {
 				t.failed = nil
 
 				valid, list := t.buildPlusList(a.a, false)
-				// If the command template has {q}, we run the command even when the
-				// query string is empty.
 				if !valid {
-					_, query := hasPreviewFlags(a.a)
-					valid = query
+					// We run the command even when there's no match
+					// 1. If the template doesn't have any slots
+					// 2. If the template has {q}
+					slot, _, query := hasPreviewFlags(a.a)
+					valid = !slot || query
 				}
 				if valid {
 					command := replacePlaceholder(a.a,
@@ -2095,7 +2097,7 @@ func (t *Terminal) Loop() {
 
 		if queryChanged {
 			if t.isPreviewEnabled() {
-				_, q := hasPreviewFlags(t.preview.command)
+				_, _, q := hasPreviewFlags(t.preview.command)
 				if q {
 					t.version++
 				}

test/test_go.rb

@@ -1640,6 +1640,13 @@ class TestGoFZF < TestBase
     tmux.until { |lines| lines.item_count == 553 && lines.match_count == 1 }
     tmux.until { |lines| !lines[-2].include?('(1/2)') }
   end
+
+  def test_reload_even_when_theres_no_match
+    tmux.send_keys %(: | #{FZF} --bind 'space:reload(seq 10)'), :Enter
+    tmux.until { |lines| lines.item_count.zero? }
+    tmux.send_keys :Space
+    tmux.until { |lines| lines.item_count == 10 }
+  end
 end
 
 module TestShell