fix: make the parser more robust and no longer accept invalid input silently.

Jellyfin.Plugin.SmartPlaylist/Lisp/Compiler/Parser.cs

@@ -3,7 +3,7 @@ using Jellyfin.Plugin.SmartPlaylist.Lisp;
 
 namespace Jellyfin.Plugin.SmartPlaylist.Lisp.Compiler {
     public class Parser {
-        private StringTokenStream _sts;
+        internal StringTokenStream _sts;
         public Parser(StringTokenStream tokens) {
             _sts = tokens;
         }
@@ -29,13 +29,18 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp.Compiler {
             Debug.Assert(start.value == end.value);
             Debug.Assert("\"".Contains(start.value));
             string r = "";
+            bool exit_ok = false;
             while (_sts.Available() > 0) {
                 Token<string> t = _sts.Get();
                 if (t.value == end.value) {
+                    exit_ok = true;
                     break;
                 }
                 r += t.value;
             }
+            if (!exit_ok) {
+                throw new ApplicationException($"Failed to parse string, are you missing the closing quotes? String is: {r}");
+            }
             _sts.Commit();
             return new String(r);
         }
@@ -69,11 +74,16 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp.Compiler {
             if (";".Contains(start.value)) {
                 return parse_comment(start, end);
             }
-            Debug.Assert(end != null);
+            if (end == null) {
+                throw new ApplicationException($"Don't know how to parse grouping starting with token '{start.value}'");
+            }
+
             IList<Expression> expressions = new List<Expression>();
+            bool exit_ok = false;
             while (_sts.Available() > 0) {
                 Token<string> t = _sts.Get();
                 if (t.value == end.value) {
+                    exit_ok = true;
                     _sts.Commit();
                     break;
                 }
@@ -87,7 +97,11 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp.Compiler {
                 _sts.Rewind(1);
                 expressions.Add(parse());
             }
-            return Cons.FromList(expressions);
+            var r = Cons.FromList(expressions);
+            if (!exit_ok) {
+                throw new ApplicationException($"Failed to parse grouping, are you missing some closing braces? Parsed expressions: {r}");
+            }
+            return r;
         }
 
         Expression parse_atom(AtomToken at) {

Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs

@@ -601,7 +601,11 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             throw new ApplicationException($"Not handled case '{expression}'");
         }
         public Expression eval(Parser p) {
-            return eval(p.parse());
+            Expression r = eval(p.parse());
+            if (p._sts.Available() > 0) {
+                throw new ApplicationException($"Did not consume all tokens, remaining program is {string.Join(" ", p._sts.Remainder())}");
+            }
+            return r;
         }
         public Expression eval(StringTokenStream sts) {
             return eval(new Parser(sts));

Jellyfin.Plugin.SmartPlaylist/Util/Stream.cs

@@ -56,6 +56,9 @@ namespace Jellyfin.Plugin.SmartPlaylist.Util {
         public IStream<T> Copy() {
             return new Stream<T>(_items, _cursor, _ephemeralCursor);
         }
+        public IList<T> Remainder() {
+            return _items.Skip(_cursor).ToList();
+        }
     }
 }