Whoops, execute_process() cannot return undef

If ProcessManager::execute_process() returns undef,
then the loop in Interpreter::interpret() thinks that
the command didn't get handled, and so goes on to look
for other commands. This is now corrected.

lib/PBot/Core/Interpreter.pm

@@ -550,11 +550,11 @@ sub interpret {
 sub handle_result {
     my ($self, $context, $result) = @_;
 
-    # if passed, allow $result parameter to override contextual result
+    # use context result if no result argument given
     $result //= $context->{result};
 
     # ensure we have a command result to work with
-    return if not defined $result;
+    return if not defined $result or not length $result;
 
     # preservation of consecutive whitespace is disabled by default
     $context->{preserve_whitespace} //= 0;

lib/PBot/Core/ProcessManager.pm

@@ -143,8 +143,8 @@ sub execute_process {
         # add reader handler
         $self->{pbot}->{select_handler}->add_reader($reader, sub { $self->process_pipe_reader($context->{pid}, @_) });
 
-        # return undef since reader will handle the output when child is finished
+        # return empty string since reader will handle the output when child is finished
-        return undef;
+        return '';
     }
 }
 

lib/PBot/VERSION.pm

@@ -25,8 +25,8 @@ use PBot::Imports;
 # These are set by the /misc/update_version script
 use constant {
     BUILD_NAME     => "PBot",
-    BUILD_REVISION => 4377,
+    BUILD_REVISION => 4381,
-    BUILD_DATE     => "2021-09-06",
+    BUILD_DATE     => "2021-09-07",
 };
 
 sub initialize {}