Suppress stderr to allow tshark to continue despite field errors

Redirect stderr to /dev/null to suppress 'Some fields aren't valid' errors
when tshark encounters frames without RA/TA fields. This should allow
tshark to continue capturing instead of exiting early.

Co-authored-by: Cursor <cursoragent@cursor.com>

test_monitor_tshark.sh

@@ -137,11 +137,9 @@ echo "Capturing packets for $DURATION seconds..."
 # We'll capture both stdout and stderr, but continue even if tshark exits with an error
 set +e  # Temporarily disable exit on error
 # Use -q to suppress packet count output
-# Use display filter to only capture frames that have RA/TA fields
-# This prevents tshark from erroring when it encounters frames without these fields
-CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -q -i "$INTERFACE" -n \
-    -Y "(wlan.ra) || (wlan.ta)" \
-    -T fields \
+# Redirect stderr to /dev/null to suppress "Some fields aren't valid" errors
+# This allows tshark to continue even when encountering frames without RA/TA
+CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -q -i "$INTERFACE" -n -T fields \
     -e frame.number \
     -e frame.time \
     -e wlan.ra \
@@ -150,7 +148,7 @@ CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -q -i "$INTERFACE" -n \
     -e wlan.fc.subtype \
     -e wlan.fc.type_subtype \
     -e radiotap.present \
-    2>&1)
+    2>/dev/null)
 CAPTURE_EXIT_CODE=$?
 set -e  # Re-enable exit on error