Add a new completion API for experimental plugins feature. (#5000)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/helper/ResizingTextEdit.cpp

@@ -170,8 +170,9 @@ void ResizingTextEdit::keyPressEvent(QKeyEvent *event)
             // First type pressing tab after modifying a message, we refresh our
             // completion model
             this->completer_->setModel(completionModel);
-            completionModel->updateResults(currentCompletion,
-                                           this->isFirstWord());
+            completionModel->updateResults(
+                currentCompletion, this->toPlainText(),
+                this->textCursor().position(), this->isFirstWord());
             this->completionInProgress_ = true;
             {
                 // this blocks cursor movement events from resetting tab completion

src/widgets/settingspages/PluginsPage.cpp

@@ -108,6 +108,16 @@ void PluginsPage::rebuildContent()
             warningLabel->setStyleSheet("color: #f00");
             pluginEntry->addRow(warningLabel);
         }
+        if (!plugin->error().isNull())
+        {
+            auto *errorLabel =
+                new QLabel("There was an error while loading this plugin: " +
+                               plugin->error(),
+                           this->dataFrame_);
+            errorLabel->setStyleSheet("color: #f00");
+            errorLabel->setWordWrap(true);
+            pluginEntry->addRow(errorLabel);
+        }
 
         auto *description =
             new QLabel(plugin->meta.description, this->dataFrame_);