Fix segfault when opening recent file with pattern sync; Don't show p… (#2448)

…attern selection popup when pattern is already open

This PR does two things. Most importantly, it fixes a segfault that can
be caused by opening a recent file with pattern sync enabled.
Secondly, it makes it so that the pattern selection popup does not
appear if you already have text in the pattern editor for a given
provider (due to CLI args, a project file, pattern sync, etc.). If you
open a file normally, that text field is empty and the popup will appear
so you can select a pre-made pattern like usual.

plugins/builtin/include/content/views/view_pattern_editor.hpp

@@ -40,8 +40,12 @@ namespace hex::plugin::builtin {
             return &m_editorRuntime;
         }
 
-        ui::TextEditor &getTextEditor() {
-            return m_textEditor;
+        ui::TextEditor *getTextEditor() {
+            auto provider = ImHexApi::Provider::get();
+            if (provider == nullptr)
+                return nullptr;
+
+            return &m_textEditor.get(provider);
         }
 
         bool getChangesWereParsed() const {