fixed issue 1839: catch exception if source code cannot be opened in the debugger

applications/admin/controllers/debug.py

@@ -54,9 +54,13 @@ def interact():
     filename = web_debugger.filename
     lineno = web_debugger.lineno
     if filename:
+        # prevent IOError 2 on some circuntances (EAFP instead of os.access)
+        try:
+            lines = open(filename).readlines()
+        except:
+            lines = ""
         lines = dict([(i + 1, l) for (i, l) in enumerate(
-            [l.strip("\n").strip("\r") for l
+            [l.strip("\n").strip("\r") for l in lines])])
-             in open(filename).readlines()])])
         filename = os.path.basename(filename)
     else:
         lines = {}