Edits sometimes fail in Conv demo

[Vtec234]

In the conv demo, when we place the cursor on conv => {} and attempt to insert a conv instruction using the widget, instead of making an edit correctly the edit-generating code panics with PANIC at _private.Init.Util.0.outOfBounds Init.Util:78:2: index out of bounds and jumps to the beginning of the file or another incorrect location.