[gtk/ebassi/introspection-error] Turn introspection scanner warnings into errors

[Emmanuele Bassi <ebassi src gnome org>]

commit 481b5ee11880d0e07b6e72856ad8ccb3b9ab7b9e
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue May 25 13:54:30 2021 +0100

    Turn introspection scanner warnings into errors
    
    We want to catch errors in our annotations or our API.

 gtk/meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gtk/meson.build b/gtk/meson.build
index 2bb41b03e7..9ebab3c6a2 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -1135,6 +1135,7 @@ if build_gir
   gir_args = [
     '-DGTK_COMPILATION',
     '--quiet',
+    '--warn-error',
   ]
 
   # We may build some of the dependencies as sub-projects; this means