[Dexter] Catch value error when encountering invalid address

The DexDeclareAddress command checks the value of a variable at a
certain point in the debugged program, and saves that value to be used
in other commands. If the value at that point is not a valid address
however, it currently causes an error in Dexter when we try to cast it -
this is fixed in this patch by catching the error and leaving the
address value unresolved.

Differential Revision: https://reviews.llvm.org/D127101

Author: SLTozer

cross-project-tests/debuginfo-tests/dexter/dex/command/commands/DexDeclareAddress.py

@@ -51,8 +51,10 @@ def eval(self, step_collection):
                 try:
                     watch = step.program_state.frames[0].watches[self.expression]
                 except KeyError:
-                    pass
-                else:
+                    continue
+                try:
                     hex_val = int(watch.value, 16)
-                    self.address_resolutions[self.get_address_name()] = hex_val
-                    break
+                except ValueError:
+                    hex_val = None
+                self.address_resolutions[self.get_address_name()] = hex_val
+                break