Debugger: Raise exception for invalid memory

The api doesn't expect empty arrays and doesn't validate indices
before accessing them.

Change-Id: I6d6fde9eec6d65d5db351be821fed892a77fabc1
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/debugger/cdbbridge.py

@@ -241,7 +241,10 @@ class Dumper(DumperBase):
         self.report('result={%s}' % (result))
 
     def readRawMemory(self, address, size):
-        return cdbext.readRawMemory(address, size)
+        mem = cdbext.readRawMemory(address, size)
+        if len(mem) != size:
+            raise Exception("Invalid memory request")
+        return mem
 
     def findStaticMetaObject(self, typeName):
         ptr = self.findValueByExpression('&' + typeName + '::staticMetaObject')