fix: not setting shape and dtype in config window when no image acquired

Previously, the shape and dtype of the error image were being saved.
This behavior was leading to an unclear bug for the user.

Author: WeisLeDocto

src/crappy/tool/camera_config/camera_config.py

@@ -1018,8 +1018,12 @@ def _update_img(self) -> None:
 
     ret = self._camera.get_image()
 
+    # Flag raised if no image could be grabbed
+    no_img = False
+
     # If no frame could be grabbed from the camera
     if ret is None:
+      no_img = True
       # If it's the first call, generate error image to initialize the window
       if not self._n_loops:
         self.log(logging.WARNING, "Could not get an image from the camera, "
@@ -1036,9 +1040,9 @@ def _update_img(self) -> None:
     self._n_loops += 1
     _, img = ret
 
-    if img.dtype != self.dtype:
+    if not no_img and img.dtype != self.dtype:
       self.dtype = img.dtype
-    if self.shape != img.shape:
+    if not no_img and img.shape != self.shape:
       self.shape = img.shape
 
     self._cast_img(img)