Check to see any WADs were returned before trying to fetch them.

dcc/fetch.py

@@ -4,6 +4,7 @@ import json
 import pathlib
 import shutil
 import subprocess
+import sys
 import urllib.request
 import zipfile
 
@@ -40,6 +41,8 @@ class Fetch(dcc.config.Base):
             "https://www.doomworld.com/idgames/api/" +
             "api.php?action=search&query={}&out=json".format(wad)
         )
+        if "content" not in reply:
+            sys.exit(f"No WAD named {wad} found on idgames.")
         files = reply["content"]["file"]
         if type(files) is dict:  # One result.
             return files["id"]