scan_vids: Fix syntax errors in SQL queries, handle case video is missing and update doesn't return a row

scan_vids.py

@@ -47,6 +47,8 @@ def video_exists(con: psycopg.Connection, file_path: str) -> bool:
         [file_path],
     )
     row = stmt.fetchone()
+    if not row:
+        return False
     return row["exists"]
 
 
@@ -61,7 +63,11 @@ def save_video(
     ffprobe: dict,
     hash_partial: str,
 ):
-    sql = """INSERT INTO videos(category, file_path, ffprobe, hash_partial) VALUES (%s, %s, %s, %s) ON CONFLICT(file_path) SET last_seen_at = NOW();"""
+    sql = """
+      INSERT INTO videos(category, file_path, ffprobe, hash_partial) 
+      VALUES (%s, %s, %s, %s) 
+      ON CONFLICT(file_path) DO UPDATE SET 
+        last_seen_at = NOW();"""
     con.execute(
         sql,
         [