Commander: fail immediately on error opening probe.

If opening the probe failed, for instance if the probe is already open,
then the error was logged but execution continued until another error
occurred. This change causes Commander to exit immediately in this case.

Author: flit

pyocd/commands/commander.py

@@ -35,6 +35,13 @@ class PyOCDCommander(object):
     
     Responsible for connecting the execution context, REPL, and commands, and handles connection.
     
+    Exit codes:
+    - 0 = no errors
+    - 1 = command error
+    - 2 = transfer error
+    - 3 = failed to create session (probe might not exist)
+    - 4 = failed to open probe
+    
     @todo Replace use of args from argparse with something cleaner.
     """
 
@@ -169,7 +176,9 @@ def connect(self):
             self.exit_code = 3
             return False
 
-        self._post_connect()
+        if not self._post_connect():
+            self.exit_code = 4
+            return False
 
         result = self.context.attach_session(self.session)
         if not result: