Issue #50 fix (#51)

* Fix issue #50

The new error message will be:

```
server.claro:2: Unexpected token <,>
  sup: "/",
          ^
```

Signed-off-by: Jason Steving <32336750+JasonSteving99@users.noreply.github.com>
Co-authored-by: Jason Steving <32336750+JasonSteving99@users.noreply.github.com>

src/java/com/claro/ClaroParser.cup

@@ -3934,6 +3934,34 @@ http_endpoints_list ::=
     {:
        RESULT = ImmutableMap.<IdentifierReferenceTerm, Object>builder().put(endpoint_name, path.getVal());
     :}
+
+  /*Report on unexpected trailing commas.*/
+  | identifier:endpoint_name COLON fmt_string:path COMMA:c 
+    {: 
+      Symbol currSymbol = new Symbol(
+          -1,
+          cleft,
+          cright,
+          LexedValue.create(
+            String.valueOf(c.getVal()),
+            c.getCurrentInputLine(),
+            c.getLen())
+       );
+      report_error("Syntax error: Unexpected trailing comma", currSymbol);
+    :}
+  | identifier:endpoint_name COLON STRING:path COMMA:c
+    {: 
+      Symbol currSymbol = new Symbol(
+          -1,
+          cleft,
+          cright,
+          LexedValue.create(
+            String.valueOf(c.getVal()),
+            c.getCurrentInputLine(),
+            c.getLen())
+       );
+      report_error("Syntax error: Unexpected trailing comma", currSymbol);
+    :}
   ;
 
 endpoint_handlers_block_stmt ::=