cws-status: Show error message when regex input does not match items

When no extension items were matched by the input regex, we previously
ran into a runtime error that wasn't obvious. Instead print an error
message explaining what the problem is.

1 files changed, 5 insertions, 0 deletions

diff --git a/cws-status b/cws-status
index 2434b57..17e4213 100644
--- a/cws-status
+++ b/cws-status
@@ -32,6 +32,7 @@ from lxml import html
 VERSION = '0.0.3'
 
 EX_USAGE = 64
+EX_DATAERR = 65
 EX_NOUSER = 67
 
 
@@ -119,6 +120,10 @@ for i, name in enumerate(item_names_versions):
     if re.search(regex, name):
         matched_extensions.append((name, item_statuses[i]))
 
+if len(matched_extensions) == 0:
+    print(f"error: no extensions matched the query: '{regex}'", file=sys.stderr)
+    sys.exit(EX_DATAERR)
+
 name_width = max([len(pair[0]) for pair in matched_extensions])
 column_padding = 7