Pamhyr: Fix tests and pep8.

src/Model/River.py

@@ -355,7 +355,10 @@ class River(Graph, SQLSubModel):
         )
 
     def _db_save_delete_artefact_where_not_id(self, execute, data,
-                                              table:str, els:list):
+                                              table: str, els: list):
+        if len(els) == 0:
+            return
+
         try:
             execute(
                 f"DELETE FROM {table} " +

src/config.py

@@ -116,19 +116,23 @@ class Config(SQL):
 
                 if int(release) < 3:
                     self.execute(
-                        f"INSERT OR IGNORE INTO data VALUES ('last_study', '')"
+                        "INSERT OR IGNORE INTO data "+
+                        "VALUES ('last_study', '')"
                     )
                     self.execute(
-                        f"INSERT OR IGNORE INTO data VALUES ('close_correctly', 'True')"
+                        "INSERT OR IGNORE INTO data " +
+                        "VALUES ('close_correctly', 'True')"
                     )
 
                 if int(release) < 4:
                     self.execute(
-                        f"INSERT OR IGNORE INTO data VALUES ('last_solver_name', '')"
+                        "INSERT OR IGNORE INTO data " +
+                        "VALUES ('last_solver_name', '')"
                     )
 
             self.execute(
-                f"UPDATE info SET value='{self._version}' WHERE key='version'"
+                f"UPDATE info SET value='{self._version}' " +
+                "WHERE key='version'"
             )
 
             self.commit()