Volshell: Sync errors with the CLI concerning unsatisfied requirements

Fixes #607

volatility3/cli/volshell/__init__.py

@@ -238,9 +238,14 @@ class VolShell(cli.CommandLine):
                 vollog.debug("Writing out configuration data to config.json")
                 with open("config.json", "w") as f:
                     json.dump(dict(constructed.build_configuration()), f, sort_keys = True, indent = 2)
+        except exceptions.UnsatisfiedException as excp:
+            self.process_unsatisfied_exceptions(excp)
+            parser.exit(1, f"Unable to validate the plugin requirements: {[x for x in excp.unsatisfied]}\n")
 
+        try:
             # Construct and run the plugin
-            constructed.run()
+            if constructed:
+                constructed.run()
         except exceptions.VolatilityException as excp:
             self.process_exceptions(excp)
             parser.exit(1, f"Unable to validate the plugin requirements: {[x for x in excp.unsatisfied]}\n")