img: Support null "width" and "height" attributes, rather than assert.

html2text/__init__.py

@@ -548,11 +548,9 @@ def link_url(self: HTML2Text, link: str, title: str = "") -> None:
                     self.images_with_size and ("width" in attrs or "height" in attrs)
                 ):
                     self.o("<img src='" + attrs["src"] + "' ")
-                    if "width" in attrs:
-                        assert attrs["width"] is not None
+                    if "width" in attrs and attrs["width"] is not None:
                         self.o("width='" + attrs["width"] + "' ")
-                    if "height" in attrs:
-                        assert attrs["height"] is not None
+                    if "height" in attrs and attrs["height"] is not None:
                         self.o("height='" + attrs["height"] + "' ")
                     if alt:
                         self.o("alt='" + alt + "' ")

test/images_with_size.html

@@ -8,3 +8,7 @@
 <img src='image_with_width_and_height.jpg' width='300' height='300' id='ignored-id' />
 <img src='image_with_width_and_height.jpg' id='ignored-id' />
 <img id='ignored-id' />
+
+<img src='image_with_no_width_value.jpg' width height='123' id='ignored-id' />
+<img src='image_with_no_height_value.jpg' width='123' height id='ignored-id' />
+<img src='image_with_no_dimention_values.jpg' width height id='ignored-id' />

test/images_with_size.md

@@ -3,4 +3,7 @@ src='image_with_width.jpg' width='300' alt='An image with a width attr' />
 <img src='image_with_width.jpg' height='300' alt='An image with a height attr'
 /> <img src='image_with_width_and_height.jpg' width='300' height='300' alt='An
 image with width and height' /> <img src='image_with_width_and_height.jpg'
-width='300' height='300' /> ![](image_with_width_and_height.jpg)
+width='300' height='300' /> ![](image_with_width_and_height.jpg) <img
+src='image_with_no_width_value.jpg' height='123' /> <img
+src='image_with_no_height_value.jpg' width='123' /> <img
+src='image_with_no_dimention_values.jpg' />