Update wl-paste handling and return None for some errors in grabclipboard() on Linux

Tests/test_imagegrab.py

@@ -119,3 +119,15 @@ def test_grabclipboard_wl_clipboard(self, ext) -> None:
             subprocess.call(["wl-copy"], stdin=fp)
         im = ImageGrab.grabclipboard()
         assert_image_equal_tofile(im, image_path)
+
+    @pytest.mark.skipif(
+        (
+            sys.platform != "linux"
+            or not all(shutil.which(cmd) for cmd in ("wl-paste", "wl-copy"))
+        ),
+        reason="Linux with wl-clipboard only",
+    )
+    @pytest.mark.parametrize("arg", ("text", "--clear"))
+    def test_grabclipboard_wl_clipboard_errors(self, arg):
+        subprocess.call(["wl-copy", arg])
+        assert ImageGrab.grabclipboard() is None

src/PIL/ImageGrab.py

@@ -149,29 +149,37 @@ def grabclipboard():
             session_type = None
 
         if shutil.which("wl-paste") and session_type in ("wayland", None):
-            output = subprocess.check_output(["wl-paste", "-l"]).decode()
-            mimetypes = output.splitlines()
-            if "image/png" in mimetypes:
-                mimetype = "image/png"
-            elif mimetypes:
-                mimetype = mimetypes[0]
-            else:
-                mimetype = None
-
-            args = ["wl-paste"]
-            if mimetype:
-                args.extend(["-t", mimetype])
+            args = ["wl-paste", "-t", "image"]
         elif shutil.which("xclip") and session_type in ("x11", None):
             args = ["xclip", "-selection", "clipboard", "-t", "image/png", "-o"]
         else:
             msg = "wl-paste or xclip is required for ImageGrab.grabclipboard() on Linux"
             raise NotImplementedError(msg)
 
         p = subprocess.run(args, capture_output=True)
-        err = p.stderr
-        if err:
-            msg = f"{args[0]} error: {err.strip().decode()}"
+        if p.returncode != 0:
+            err = p.stderr
+            for silent_error in [
+                # wl-paste, when the clipboard is empty
+                b"Nothing is copied",
+                # Ubuntu/Debian wl-paste, when the clipboard is empty
+                b"No selection",
+                # Ubuntu/Debian wl-paste, when an image isn't available
+                b"No suitable type of content copied",
+                # wl-paste or Ubuntu/Debian xclip, when an image isn't available
+                b" not available",
+                # xclip, when an image isn't available
+                b"cannot convert ",
+                # xclip, when the clipboard isn't initialized
+                b"xclip: Error: There is no owner for the ",
+            ]:
+                if silent_error in err:
+                    return None
+            msg = f"{args[0]} error"
+            if err:
+                msg += f": {err.strip().decode()}"
             raise ChildProcessError(msg)
+
         data = io.BytesIO(p.stdout)
         im = Image.open(data)
         im.load()