1081767 - JavaScript error: chrome://messenger/content/nsContextMenu.js, line 693: TypeError: item is null

Status: RESOLVED WORKSFORME

Description

[ISHIKAWA, Chiaki]

During |make mozmill| test of locally built DEBUG BUILD of C-C TB
I see

JavaScript error: chrome://messenger/content/nsContextMenu.js, line 693: TypeError: item is null

( I see a similar error once more in a different place of the log
but it repors a different line #: 694 ??? off by one???)

mailContextMenus.js is
This one for TB: comm-central/mail/base/content/mailContextMenus.js
               : comm-central/suite/mailnews/mailContextMenus.js

Funny, though, line 693 is at the end of the file (!)
Actually, the file has only 619 lines.???

TIA

Comment 1

[ISHIKAWA, Chiaki]

Sorry I was looking at a wrong file.

nsContextMenus.js vs mailContextMenus.js:

Correct file nsContextMenu.js:

  684	  /**
  685	   * Set a DOM node's hidden property by passing in the node's id or the
  686	   * element itself.
  687	   * @param aItemOrId
  688	   *        a DOM node or the id of a DOM node
  689	   * @param aShow
  690	   *        true to show, false to hide
  691	   */
  692	  showItem : function CM_showItem(aItemOrId, aShow) {
  693	    var item = aItemOrId.constructor == String ? document.getElementById(aItemOrId) : aItemOrId;
  694	    item.hidden = !aShow;
  695	  },

So item becomes null on 693.

Comment 2

[:aceman]

Which test causes this message?
I think you could put a "debugger;" statement (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/debugger) into the showItem function so see what is the caller of the function.

Comment 3

[ISHIKAWA, Chiaki]

(In reply to :aceman from comment #2)
> Which test causes this message?
> I think you could put a "debugger;" statement
> (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/
> Statements/debugger) into the showItem function so see what is the caller of
> the function.

Thank you for the suggestion for "debugger;" statement. This is an important addition to my arsenal to fight the bugs :-)

Anyway, for like a week or so after the refresh of the source tree, the bug has disappeared.
When it appeared in the middle of October, [my log showed 13 October],
it appeared in the following tests and I show lines immediately preceding and following the mentioned errors:


TEST-START | /REF-COMM-CENTRAL/comm-central/mail/test/mozmill/message-header/test-message-header.js | test_msg_id_context_menu

	   ...

JavaScript strict warning: chrome://messenger/content/nsContextMenu.js, line 103: ReferenceError: reference to undefined property this.onEditableArea
JavaScript error: chrome://messenger/content/nsContextMenu.js, line 693: TypeError: item is null
JavaScript strict warning: resource://gre/modules/FormHistory.jsm, line 639: ReferenceError: reference to undefined property change.guid
[7319] WARNING: 1 sort operation has occurred for the SQL statement '0x7f6fc4046c40'.  See https://developer.mozilla.org/En/Storage/Warnings details.: file /REF-COMM-CENTRAL/comm-central/mozilla/storage/src/mozStoragePrivateHelpers.cpp, line 114

TEST-START | /REF-COMM-CENTRAL/comm-central/mail/test/mozmill/message-window/test-commands.js | test_copy_eml_message
Step Pass: {"function": "Controller.keypress()"}

...

JavaScript strict warning: chrome://messenger/content/nsContextMenu.js, line 103: ReferenceError: reference to undefined property this.onEditableArea
JavaScript error: chrome://messenger/content/nsContextMenu.js, line 694: TypeError: item is null
Step Pass: {"function": "controller.rightClick()"}
Step Pass: {"function": "controller.click()"}
Step Pass: {"function": "controller.click()"}
GetDiskSpaceAvailable returned: 2476208128 bytes
Step Pass: {"function": "controller.click()"}
Step Pass: {"function": "Controller.keypress()"}
Step Pass: {"function": "Controller.keypress()"}


You see both of the errors are preceded by 
JavaScript's ReferenceError: reference to undefined property this.onEditableArea;

If I am not mistaken this bug with onEditableArea has been fixed.
I suspect that "item is null" was triggered by the error.

Since I don't see it anymore in the tree for the last week or so,
I am closing it.

Thank you for your advice about "debug;" statement.
I may want to use this for debugging the issue
https://bugzilla.mozilla.org/show_bug.cgi?id=936007
 JavaScript strict warning: chrome://global/content/bindings/tree.xml, line 50: reference to undefined property this.treeBoxObject.columns

which got me stumped.