Pollutant: Fix db create.

src/Model/Pollutants/Pollutants.py

@@ -319,8 +319,11 @@ class Pollutants(SQLSubModel):
           )
         """)
 
+        if ext != "":
             return True
 
+        return cls._create_submodel(execute)
+
     @classmethod
     def _db_update(cls, execute, version, data=None):
         major, minor, release = version.strip().split(".")