[gnome-builder] foundry: Fix warn on 'populate_diagnostics' logic

[Christian Hergert <chergert src gnome org>]

commit 162d18f633991515b6a0fe3378dc5d40e8a0b43e
Author: Veli Tasalı <veli tasali gmail com>
Date:   Mon Feb 28 01:44:03 2022 +0300

    foundry: Fix warn on 'populate_diagnostics' logic
    
    This fixes the problem where IdeDiagnosticTool
    warns when 'populate_diagnostics' is implemented
    instead of warning when it is not.

 src/libide/foundry/ide-diagnostic-tool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/libide/foundry/ide-diagnostic-tool.c b/src/libide/foundry/ide-diagnostic-tool.c
index a556e6854..e40c0cf71 100644
--- a/src/libide/foundry/ide-diagnostic-tool.c
+++ b/src/libide/foundry/ide-diagnostic-tool.c
@@ -163,7 +163,7 @@ ide_diagnostic_tool_constructed (GObject *object)
 
   G_OBJECT_CLASS (ide_diagnostic_tool_parent_class)->constructed (object);
 
-  if (IDE_DIAGNOSTIC_TOOL_GET_CLASS (self)->populate_diagnostics)
+  if (!IDE_DIAGNOSTIC_TOOL_GET_CLASS (self)->populate_diagnostics)
     g_critical ("%s inherits from IdeDiagnosticTool but does not implement populate_diagnostics(). This will 
not work.",
                 G_OBJECT_TYPE_NAME (self));
 }