using python for removal of empty lines because it did not work

opuscleaner/filters/remove_empty_lines.json

@@ -1,6 +1,6 @@
 {
     "description": "Remove lines that are empty or just whitespace on either side",
     "type": "bilingual",
-    "command": "grep -avE $'^\\\\s*\\t|\\t\\\\s*$|^[^\\t]*$'",
+    "command": "./remove_empty_lines.py",
     "parameters": {}
-}
+}

opuscleaner/filters/remove_empty_lines.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+import sys
+
+def main():
+    for line in sys.stdin:
+        fields = line.strip("\r\n").split("\t")
+        ok = True
+        for field in fields:
+            if not field.strip():
+                ok = False
+                break
+        if ok:
+            sys.stdout.write(line)
+
+if __name__ == '__main__':
+    main()