feat: gracefully fallback when integration dependencies are not met

If a dependency for an integration is missing, fallback gracefully so as
not to interrupt user experience

conf.d/tailscale.fish

@@ -14,6 +14,10 @@
 
 # fish completion for tailscale                            -*- shell-script -*-
 
+if not type -q tailscale
+    return
+end
+
 function __tailscale_debug
     set -l file "$BASH_COMP_DEBUG_FILE"
     if test -n "$file"

conf.d/wakatime.fish

@@ -29,7 +29,6 @@ function __register_wakatime_fish_before_exec -e fish_postexec
   else if type -p ~/.wakatime/wakatime-cli 2>&1 > /dev/null
     set wakatime_path (type -p ~/.wakatime/wakatime-cli)
   else
-    echo "wakatime command not found. Please read \"https://wakatime.com/terminal\" and install wakatime."
     return 1
   end
 

conf.d/zoxide.fish

@@ -1,8 +1,13 @@
 # =============================================================================
 #
+#
 # Utility functions for zoxide.
 #
 
+if not type -q zoxide
+    return
+end
+
 # pwd based on the value of _ZO_RESOLVE_SYMLINKS.
 function __zoxide_pwd
     builtin pwd -L