Fix #659 (PageImage.debug_tablefinder())

Thanks to @rneumann7 for flagging!

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
+## [0.7.1] - 2022-05-31
+
+### Fixed
+
+- Fix bug when calling `PageImage.debug_tablefinder()` (i.e., with no parameters). ([#659](https://github.com/jsvine/pdfplumber/issues/659)) [h/t @rneumann7]
+
 ## [0.7.0] - 2022-05-27
 
 ### Added

pdfplumber/display.py

@@ -282,7 +282,7 @@ class PageImage:
     ) -> "PageImage":
         if isinstance(tf, TableFinder):
             finder = tf
-        elif isinstance(tf, (TableSettings, dict)):
+        elif tf is None or isinstance(tf, (TableSettings, dict)):
             finder = self.page.debug_tablefinder(tf)
         else:
             raise ValueError(

tests/test_display.py

@@ -40,6 +40,8 @@ class Test(unittest.TestCase):
         finder = TableFinder(self.im.page, settings)
         self.im.debug_tablefinder(finder)
 
+        self.im.debug_tablefinder(None)
+
         with pytest.raises(ValueError):
             self.im.debug_tablefinder(0)