in src/connectors/sheets-connector.js [207:221]
getTabLastRow(tabId) {
let tabConfig = this.tabs[tabId];
let sheet = this.getSheet(tabId);
let sheetValues = sheet.getDataRange().getValues();
sheetValues = sheetValues.map(rowValues => {
let values = rowValues.join('').trim();
return !!values;
});
let rowIndex = sheetValues.length;
while (!sheetValues[rowIndex - 1]) {
rowIndex--;
}
return rowIndex;
}