in app/addons/components/components/ace-worker-mango.js [262:279]
function validateDelta(docLines, delta) {
if (delta.action != "insert" && delta.action != "remove")
throwDeltaError(delta, "delta.action must be 'insert' or 'remove'");
if (!(delta.lines instanceof Array))
throwDeltaError(delta, "delta.lines must be an Array");
if (!delta.start || !delta.end)
throwDeltaError(delta, "delta.start/end must be an present");
var start = delta.start;
if (!positionInDocument(docLines, delta.start))
throwDeltaError(delta, "delta.start must be contained in document");
var end = delta.end;
if (delta.action == "remove" && !positionInDocument(docLines, end))
throwDeltaError(delta, "delta.end must contained in document for 'remove' actions");
var numRangeRows = end.row - start.row;
var numRangeLastLineChars = (end.column - (numRangeRows == 0 ? start.column : 0));
if (numRangeRows != delta.lines.length - 1 || delta.lines[numRangeRows].length != numRangeLastLineChars)
throwDeltaError(delta, "delta.range must match delta lines");
}