[ImageGallery] Do not fill intrinsics model until it has been instantiated

In some cases, like when opening the most recent file from the command
line, switching the color palette or hot reloading, the intrinsics
might be parsed and ready to populate the intrinsics' `TableModel` while
the model itself is being instantiated.

To prevent crashes, we forbid operations on the `TableModel` until it has
been fully instantiated.

meshroom/ui/qml/ImageGallery/ImageGallery.qml

@@ -75,6 +75,11 @@ Panel {
     }
 
     function populate_model() {
+        if (!intrinsicModel.ready) {
+            // If the TableModel is not done being instantiated, do nothing
+            return
+        }
+
         intrinsicModel.clear()
         for (var intr in parsedIntrinsic) {
             intrinsicModel.appendRow(parsedIntrinsic[intr])
@@ -569,6 +574,8 @@ Panel {
 
             TableModel {
                 id : intrinsicModel
+                property bool ready: false
+
                 // Hardcoded default width per column
                 property var columnWidths: [105, 75, 75, 75, 60, 60, 60, 60, 200, 60, 60, 60]
                 property var columnNames: [
@@ -599,6 +606,13 @@ Panel {
                 TableModelColumn { display: function(modelIndex){return parsedIntrinsic[modelIndex.row][intrinsicModel.columnNames[10]]} }
                 TableModelColumn { display: function(modelIndex){return parsedIntrinsic[modelIndex.row][intrinsicModel.columnNames[11]]} }
                 //https://doc.qt.io/qt-5/qml-qt-labs-qmlmodels-tablemodel.html#appendRow-method
+
+                Component.onCompleted: {
+                    ready = true
+                    // Triggers "populate_model" in case the intrinsics have been filled while the model was
+                    // being instantiated
+                    root.populate_model()
+                }
             }
 
             //CODE FOR HEADERS