Many bug fixes (#25)

* open file in write mode

Open server list in write mode.

* various bug fixes

- raise ValueError rather then Exception.
- "Invalid render distance: (distance)" instead of "Invalid render distance".
- open server list in read-only mode.

planet/launcher.py

@@ -58,7 +58,7 @@ def set_username(env, username: str = "StevePi"):
 
 def set_render_distance(env, distance: str = "SHORT"):
     if distance.upper() not in ["TINY", "SHORT", "NORMAL", "FAR"]:
-        raise Exception("Invalid render distance")
+        raise ValueError("Invalid render distance: {0}".format(distance))
     else:
         env["MCPI_RENDER_DISTANCE"] = distance
         return env

planet/main.py

@@ -539,7 +539,7 @@ class Planet(QMainWindow):
         self.serversedit.textChanged.connect(
             self.save_servers
         )  # Connect on change to the save function
-        with open(f"/home/{USER}/.minecraft-pi/servers.txt") as servers:
+        with open(f"/home/{USER}/.minecraft-pi/servers.txt", 'r') as servers:
             self.serversedit.setPlainText(
                 servers.read()
             )  # Set the text of the text editing area