Better error message when pygments style is not found

kittens/diff/highlight.py

@@ -16,10 +16,21 @@ from kitty.rgb import color_as_sgr, parse_sharp
 from .collect import Segment, data_for_path, lines_for_path
 
 
+class StyleNotFound(Exception):
+    pass
+
+
 class DiffFormatter(Formatter):
 
     def __init__(self, style='default'):
-        Formatter.__init__(self, style=style)
+        try:
+            Formatter.__init__(self, style=style)
+            initialized = True
+        except ClassNotFound:
+            initialized = False
+        if not initialized:
+            raise StyleNotFound('pygments style "{}" not found'.format(style))
+
         self.styles = {}
         for token, style in self.style:
             start = []

kittens/diff/main.py

@@ -241,8 +241,14 @@ class DiffHandler(Handler):
                 self.restore_position = None
             self.draw_screen()
             if initialize_highlighter is not None and not self.highlighting_done:
+                from .highlight import StyleNotFound
                 self.highlighting_done = True
-                initialize_highlighter(self.opts.pygments_style)
+                try:
+                    initialize_highlighter(self.opts.pygments_style)
+                except StyleNotFound as e:
+                    self.report_traceback_on_exit = str(e)
+                    self.quit_loop(1)
+                    return
                 self.start_job('highlight', highlight_collection, self.collection, self.opts.syntax_aliases)
         elif job_id == 'highlight':
             hdata = job_result['result']