Raise better error if icevision not installed if module isn't found…

… (loading data) (#1474)

* Add requires(icevision) for loading data (icevision integration)

* Add changelog entry

CHANGELOG.md

@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ### Fixed
 
+- Fixed the error message to suggest installing `icevision`, if it's not found while loading data ([#1474](https://github.com/Lightning-AI/lightning-flash/pull/1474))
 - Fixed compatibility with `torchmetrics==1.10.0` ([#1469](https://github.com/Lightning-AI/lightning-flash/pull/1469))
 
 

flash/core/integrations/icevision/data.py

@@ -20,7 +20,7 @@
 from flash.core.data.utilities.loading import IMG_EXTENSIONS, load_image, NP_EXTENSIONS
 from flash.core.data.utilities.paths import list_valid_files
 from flash.core.integrations.icevision.transforms import from_icevision_record
-from flash.core.utilities.imports import _ICEVISION_AVAILABLE
+from flash.core.utilities.imports import _ICEVISION_AVAILABLE, requires
 
 if _ICEVISION_AVAILABLE:
     from icevision.core.record import BaseRecord
@@ -33,6 +33,7 @@ class IceVisionInput(Input):
     num_classes: int
     labels: list
 
+    @requires("icevision")
     def load_data(
         self,
         root: str,