Fixes check syntax bug

collects/drracket/private/syncheck/traversals.rkt

@@ -1228,6 +1228,7 @@
                  (when ed
                    (define pos (syntax-position var))
                    (define span (syntax-span var))
+                   (when (and pos span)
                      (define start (- pos 1))
                      (define fin (+ start span))
                      (define loc (list ed start fin))
@@ -1235,7 +1236,7 @@
                       id-to-sets
                       var
                       (set-add (module-identifier-mapping-get id-to-sets var set)
-                             loc)))))))
+                               loc))))))))
           (module-identifier-mapping-for-each
            id-to-sets
            (λ (id locs)

collects/tests/drracket/syncheck-direct.rkt

@@ -66,3 +66,24 @@
                                (let ([y 1]) y)))))))
      (done))
    add-arrow-called?))
+
+(check-not-exn
+ (λ ()
+   (define annotations
+     (new (class (annotations-mixin object%)
+            (super-new)
+            (define/override (syncheck:find-source-object stx)
+              stx))))
+   
+   (define base-namespace (make-base-namespace))
+   (define-values (add-syntax done)
+     (make-traversal base-namespace #f))
+   
+   (parameterize ([current-annotations annotations]
+                  [current-namespace base-namespace])
+     (eval '(require (for-syntax racket/base)))
+     (add-syntax
+      (expand
+       '(let-syntax ([m (λ (_) #`(let ([x 1]) x))])
+          (m))))
+     (done))))