make error message about incorrect powerlevel10k loading visible in more cases

internal/p10k.zsh

@@ -8122,13 +8122,14 @@ _p9k_init() {
   _p9k_init_vcs
 
   if (( _p9k__instant_prompt_disabled )); then
-    unset __p9k_instant_prompt_erased
+    (( _POWERLEVEL9K_DISABLE_INSTANT_PROMPT )) && unset __p9k_instant_prompt_erased
     _p9k_delete_instant_prompt
     _p9k_dumped_instant_prompt_sigs=()
   fi
 
   if (( $+__p9k_instant_prompt_erased )); then
     unset __p9k_instant_prompt_erased
+    {
       >&2 echo -E - ""
       >&2 echo -E - "${(%):-[%1FERROR%f]: When using instant prompt, Powerlevel10k must be loaded before the first prompt.}"
       >&2 echo -E - ""
@@ -8140,7 +8141,14 @@ _p9k_init() {
       else
         >&2 echo    - "${(%):-    See https://github.com/romkatv/powerlevel10k/blob/master/README.md#installation.}"
       fi
-    if (( $+functins[zplugin] )); then
+      if (( $+zsh_defer_options )); then
+        >&2 echo -E - ""
+        >&2 echo -E - "${(%):-    NOTE: Do not use %1Fzsh-defer%f to load %Upowerlevel10k.zsh-theme%u.}"
+      elif (( $+functins[zinit] )); then
+        >&2 echo -E - ""
+        >&2 echo -E - "${(%):-    NOTE: If using %2Fzinit%f to load %3F'romkatv/powerlevel10k'%f, %Bdo not apply%b %1Fice wait%f.}"
+      elif (( $+functins[zplugin] )); then
+        >&2 echo -E - ""
         >&2 echo -E - "${(%):-    NOTE: If using %2Fzplugin%f to load %3F'romkatv/powerlevel10k'%f, %Bdo not apply%b %1Fice wait%f.}"
       fi
       >&2 echo -E - ""
@@ -8160,6 +8168,7 @@ _p9k_init() {
       >&2 echo -E - "${(%):-    * You %Bwill%b see this error message every time you start zsh.}"
       >&2 echo -E - "${(%):-    * Zsh will start %Bslowly%b.}"
       >&2 echo -E - ""
+    } 2>>$TTY
   fi
 }