Debugger: Fix LLDB listing registers when no frame is selected

Change-Id: I6c3d193a2622ed07c34e68bf8b5780d55520e4f2
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/debugger/lldbbridge.py

@@ -1267,12 +1267,17 @@ class Dumper(DumperBase):
         self.put('],partial="%d"' % isPartial)
         self.reportResult(self.output, args)
 
+
     def fetchRegisters(self, args=None):
-        if self.process is None:
+        if not self.process:
-            result = 'process="none"'
+            self.reportResult('process="none",registers=[]', args)
-        else:
+            return
+
         frame = self.currentFrame()
-            if frame:
+        if not frame or not frame.IsValid():
+            self.reportResult('frame="none",registers=[]', args)
+            return
+
         result = 'registers=['
         for group in frame.GetRegisters():
             for reg in group:
@@ -1284,6 +1289,7 @@ class Dumper(DumperBase):
         result += ']'
         self.reportResult(result, args)
 
+
     def setRegister(self, args):
         name = args["name"]
         value = args["value"]