Remove catch of ChannelException

This catch block may hide errors that the user makes. If the parent died, another exception will be generated and caught below when trying to send the ExitFailure object.

lib/Context/Internal/process-runner.php

@@ -90,9 +90,6 @@ Loop::run(function () use ($argc, $argv) {
         }
 
         $result = new Sync\ExitSuccess(yield call($callable, $channel));
-    } catch (Sync\ChannelException $exception) {
-        \trigger_error(E_USER_ERROR, "Communication with the parent failed");
-        exit(1);
     } catch (\Throwable $exception) {
         $result = new Sync\ExitFailure($exception);
     }