Crash when insert an invalid char in array, and object

[stokhos]

Insert invalid cha c in array and object will cause the problem.

This problem is related to cursor location.

sapling/src/editor/dag.rs

Lines 410 to 415 in 9fed519

	if !parent.is_valid_child(cursor_index, c) {
	// Short circuit if `c` couldn't be a valid child of the cursor
	return Err(EditErr::CannotBeChild {
	c,
	parent_name: cursor.display_name(),
	});

``

[kneasle]

This crashes regardless of which node is under the cursor dw about this - I was getting confused with a different crash bug. I've found a fix, and I'm making regression tests for this.

[kneasle]

Actually, if #63 is fixed then this bug will not be possible.

[kneasle]

Oh whoops, this was accidentally closed because of some silly commit wording 😆 who knew.

[kneasle]

I've been doing some digging, and the cause of the problem is that Json::is_valid_child returns a blanket true if the node being inserted into is Json::Object or Json::Array. By extension, this also returns true for invalid characters, and so an error is not returned, and so Json::from_char is called and then unwrapped, causing the crash.

This will be fixed along with #63, because Json::is_valid_child will take a type-safe intermediate type and so it isn't possible to insert an invalid node.