fix textinput.CurrentSuggestion() panic

When suggestions are not yet set CurrentSuggestion() will panic. This change fixes that with a guard and returns an empty string when there is no current suggestion.

textinput/textinput_test.go

@@ -0,0 +1,32 @@
+package textinput
+
+import (
+	"testing"
+)
+
+func Test_CurrentSuggestion(t *testing.T) {
+	textinput := New()
+	textinput.ShowSuggestions = true
+
+	suggestion := textinput.CurrentSuggestion()
+	expected := ""
+	if suggestion != expected {
+		t.Fatalf("Error: expected no current suggestion but was %s", suggestion)
+	}
+
+	textinput.SetSuggestions([]string{"test1", "test2", "test3"})
+	suggestion = textinput.CurrentSuggestion()
+	expected = ""
+	if suggestion != expected {
+		t.Fatalf("Error: expected no current suggestion but was %s", suggestion)
+	}
+
+	textinput.SetValue("test")
+	textinput.updateSuggestions()
+	textinput.nextSuggestion()
+	suggestion = textinput.CurrentSuggestion()
+	expected = "test2"
+	if suggestion != expected {
+		t.Fatalf("Error: expected first suggestion but was %s", suggestion)
+	}
+}