better message for nonexistent files on the commandline.

Author: timo

src/HLL/Compiler.pm

@@ -445,10 +445,22 @@ class HLL::Compiler does HLL::Backend::Default {
         my @files := nqp::islist($files) ?? $files !! [$files];
         $!user_progname := nqp::join(',', @files);
         my @codes;
-        for @files {
+        for @files -> $filename {
+            if !nqp::stat($filename, 0) {
+                nqp::say("Could not stat $filename: No such file or directory.");
+                nqp::exit(1);
+            }
             my $err := 0;
+            my $in-handle;
+            try {
+                $in-handle := nqp::open($filename, 'r');
+                CATCH {
+                    nqp::say("Could not open $filename. $_");
+                    $err := 1;
+                }
+            }
+            nqp::exit(1) if $err;
             try {
-                my $in-handle := nqp::open($_, 'r');
                 nqp::setencoding($in-handle, $encoding);
                 nqp::push_s(@codes, nqp::readallfh($in-handle));
                 nqp::closefh($in-handle);