Don't attempt to enable application mode if it isn't available, see #263.

modules/editor/init.zsh

@@ -144,18 +144,20 @@ zle -N editor-info
 # Ensures that $terminfo values are valid and updates editor information when
 # the keymap changes.
 function zle-keymap-select zle-line-init zle-line-finish {
-  # The terminal must be in application mode when ZLE is active for $terminfo
-  # values to be valid.
-  case "$0" in
-    (zle-line-init)
-      # Enable terminal application mode.
-      echoti smkx
-    ;;
-    (zle-line-finish)
-      # Disable terminal application mode.
-      echoti rmkx
-    ;;
-  esac
+  # If it has the respective capability, the terminal should be in application
+  # mode when ZLE is active for $terminfo values to be valid.
+  if (( ${+terminfo[smkx]} )) && (( ${+terminfo[rmkx]} )); then
+    case "$0" in
+      (zle-line-init)
+        # Enable terminal application mode.
+        echoti smkx
+      ;;
+      (zle-line-finish)
+        # Disable terminal application mode.
+        echoti rmkx
+      ;;
+    esac
+  fi
 
   # Update editor information.
   zle editor-info