Additional check to avoid evaluating an expression if it is a comment (#3494)

Author: rgroothuijsen

lib/less/parser/parser.js

@@ -2321,6 +2321,11 @@ const Parser = function Parser(context, imports, fileInfo) {
                         continue;
                     }
                     e = this.addition() || this.entity();
+
+                    if (e instanceof tree.Comment) {
+                        e = null;
+                    }
+
                     if (e) {
                         entities.push(e);
                         // operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here

test/less/errors/invalid-color-with-comment.less

@@ -0,0 +1 @@
+.test {color: #fffff /* comment */ ;}

test/less/errors/invalid-color-with-comment.txt

@@ -0,0 +1,2 @@
+ParseError: Unrecognised input in {path}invalid-color-with-comment.less on line 1, column 36:
+1 .test {color: #fffff /* comment */ ;}