[__sensible_editor] Improve error message when a basename of an editor not in the alternatives is provided

cdist/conf/type/__sensible_editor/explorer/editor_path

@@ -78,17 +78,24 @@ then
 	if ! $is_abspath
 	then
 		# First, try to resolve the absolute path using $editors.
+		while true
+		do
 			for e in $editors
 			do
 				if test "$(basename "${e}")" = "${editor}"
 				then
 					editor="${e}"
-				break
+					break 2  # break out of both loops
 				fi
 			done
+
+			# Iterating through alternatives did not yield a result
+			editor_no_alternative "${editor}"
+			break
+		done
 	fi
 
-	# Check if path is present
+	# Check if editor is present
 	test -f "${editor}" || editor_missing "${editor}"
 
 	for e in $editors