A short description of the issue:

Multiple bugs in EmbeddedChartBuilder API. All bugs in the API are denoted with "of course... 🤦", because there are so many. I put them into single ticket as they are related. I also attach the spreadsheet wihich I used for testing the script here: https://docs.google.com/spreadsheets/d/1qENMRhHlctF1tzAZL5kzY2t-okcSAQSItjBp0CS_5F4/edit?usp=sharing

/** @OnlyCurrentDoc */
/*global SpreadsheetApp, Logger, Charts */
// TODO review Janci Gasper?
// Warning: The API for Charts in Google Sheets is truly terrible and buggy.
// all bugs in the API are denoted with "of course... 🤦"

const VERSION = "0.8";

class MyLogger {
  constructor() {
    let logsSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("#Logs");
    if (logsSheet == null) {
      logsSheet = SpreadsheetApp.getActiveSpreadsheet().insertSheet("#Logs");
    }

    logsSheet.setFrozenRows(1);
    const heading = "Chart coloring - app script logs                             ";
    logsSheet.getRange("A1").setFontWeight("bold").setValue(heading);
    logsSheet.autoResizeColumn(1);

    const logRange = logsSheet.getRange("A2:A");
    const logRangeValues = logRange.getValues();
    let ct = 0;

    while (logRangeValues[ct] && logRangeValues[ct][0] != "") {
      ct++;
    }

    const now = new Date();
    this.logToThisCell = logRange.getCell(ct + 1, 1);
    this.logStringBuffer = now.toUTCString() + ": ";
    this.logsSheet = logsSheet;

    Logger.log("VERSION: " + VERSION);
    this.logStringBuffer = this.logStringBuffer + "\n" + "VERSION: " + VERSION;
  }

  log(msg) {
    this.logStringBuffer = this.logStringBuffer + "\n" + msg;
    Logger.log(msg);
  }

  flush() {
    this.logToThisCell.setValue(this.logStringBuffer);
    Logger.log("MyLogger flushed.");
    this.logsSheet.autoResizeColumn(1);
  }
}

function onOpen() {
  SpreadsheetApp.getUi()
    .createAddonMenu()
    .addItem("Color all charts", "colorChartsWithPallete")
    .addToUi();

  colorChartsWithPallete();
}

/**
 * A custom function that can be called as a formula from within a sheet.
 * @param event Cell that if changed the function is (re)triggered, the
 * parameter content is otherwise not used by this function.
 * @return Table of Chart titles, Chart types, ChartIDs and Sheets of
 * all charts within the document.
 * @customfunction
 */
function GETALLCHARTS(event) {
  const chartTable = new Array();
  chartTable.push(["Chart title", "Chart type", "ChartID", "Sheet"]);

  for (const sheet of SpreadsheetApp.getActiveSpreadsheet().getSheets()) {
    for (const chart of sheet.getCharts()) {
      const row = new Array();
      row.push(chart.getOptions().get("title"));
      row.push(chart.modify().getChartType());
      row.push(chart.getChartId().toString());
      row.push(sheet.getName());
      chartTable.push(row);
    }
  }

  return chartTable;
}

function getChartInfo(chart) {
  return (
    "{ Chart title: '" +
    chart.getOptions().get("title") +
    "', " +
    "Chart type: " +
    chart.modify().getChartType() +
    ", " +
    "ChartID: " +
    chart.getChartId().toString() +
    " }"
  );
}

function createPallete() {
  const palleteSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("#Pallete");

  palleteSheet.setFrozenRows(1);
  const headings = [
    [
      "ChartID (script input)   ",
      "Pallete array (script input)                                            ",
      "Chart title                              ",
      "Chart type       ",
      "Sheet               ",
      "All charts (generated), formula: =GETALLCHARTS(F1)     ",
    ],
  ];

  palleteSheet.getRange("A1:Z1").setFontWeight("bold").setBackground("#cccccc");
  palleteSheet.getRange("A1:F1").setValues(headings);
  palleteSheet.getRange("F2").setValue("=GETALLCHARTS(F1)");
  palleteSheet
    .getRange("C2")
    .setValue(
      '=MAP(A2:A, LAMBDA(id, if(id <> "", query({F3:I}, "SELECT Col1, Col2, Col4 WHERE Col3 = \'" & id & "\'"), "")))',
    );
  palleteSheet.getRange("F2:I2").setFontWeight("bold");
  palleteSheet.autoResizeColumns(1, 10);
}


function colorChartsWithPallete() {
  const myLogger = new MyLogger();
  myLogger.log("--- colorPieChartsWithPallete() started ---");

  let palleteSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("#Pallete");
  if (palleteSheet == null) {
    palleteSheet = SpreadsheetApp.getActiveSpreadsheet().insertSheet("#Pallete");
    myLogger.log("--- CREATING NEW #Pallete sheet ---");
    createPallete();
  }

  const palleteTable = palleteSheet.getRange("A2:B").getValues();
  const palleteMap = new Map(palleteTable);

  for (const sheet of SpreadsheetApp.getActiveSpreadsheet().getSheets()) {
    for (let chart of sheet.getCharts()) {
      const chartID = chart.getChartId().toString();

      if (palleteMap.has(chartID)) {

        if (palleteMap.has(chartID)) {
          const pallete = palleteMap.get(chartID);
          const colors = JSON.parse(pallete);

          // using chart.modify().setOption('colors', colors).build(); directly is broken...
          // Also, the script appears to be working incorrectly e.g. for BAR and COLUMN charts
          // TODO - add tests for all supported chart types
          // it +- works only for pie charts... afterall :D
          switch (chart.modify().getChartType()) {
              case Charts.ChartType.PIE:
                  chart = chart.modify().asPieChart().setColors(colors).build();
                  break;
              // THE CODE FOR COLORING LINE CHARTS IS UNRELIABLE FOR SOME REASON - SOMETIMES
              // IT WORKS ONLY ON 3RD TIME... of course... 🤦
              // but it could theoretically be used when careful...
              // Maybe removing and inserting the chart explicitly would help?
              // or maybe the colors array needs to be crafted differently for line chart?
              // case Charts.ChartType.LINE:
              //     chart = chart.modify().asLineChart().setColors(colors).build();
              //     sheet.updateChart(chart);
              //     break;
              case Charts.ChartType.BAR:
                  chart = chart.modify().asBarChart().setColors(colors).build();
                  break;
              // chart.getOptions().get("colors") for colmun charts throws unknown
              // excetions sometimes... of course... 🤦
              // case Charts.ChartType.COLUMN:
              //     chart = chart.modify().asColumnChart().setColors(colors).build();
              //     break;
              case Charts.ChartType.SCATTER:
                  chart = chart.modify().asScatterChart().setColors(colors).build();
                  break;
              case Charts.ChartType.AREA:
                  chart = chart.modify().asAreaChart().setColors(colors).build();
                  break;
              case Charts.ChartType.HISTOGRAM:
                  chart = chart.modify().asHistogramChart().setColors(colors).build();
                  break;
              // broken - crashes the spreadsheet service, of course... 🤦
              // case COMBO:
              //     chart = chart.modify().asComboChart().setColors(colors).build();
              //     break;
              default:
                  myLogger.log(
                      "Error - ChartType is not supported. Chart: " + getChartInfo(chart)
                  );
                  continue;
          }

          myLogger.log(
            "chart.modify().as***Chart().setColors( [ " +
              colors.toString() +
              " ] ), called for a chart: " +
              getChartInfo(chart)
          );
          // There are no getColors() counterparts for setColors() and chart.getOptions().get("colors")
          // returns null most of the time... of course... 🤦
          myLogger.log(
            "chart.getOptions().get('colors'): [ " + 
              chart.getOptions().get("colors") +
              " ], chart: " + getChartInfo(chart)
          );

          sheet.updateChart(chart);
          myLogger.log("Chart " + chart.getChartId() + " updated.");
        }

        // THIS METHOD USING chart().modify().setOption() IS BUGGY for some reason
        // (it does not color all the slices of the pie chart) it behaves as a race condition
        // of course... 🤦
        // charts that do not have the colors option are commented out
        // const SUPPORTED_CHART_TYPES = new Set([
        //   Charts.ChartType.TIMELINE, // supports
        //   Charts.ChartType.AREA, // supports
        //   Charts.ChartType.BAR, // supports
        //   Charts.ChartType.BUBBLE, // supports
        //   Charts.ChartType.CANDLESTICK, // supports
        //   // Charts.ChartType.COLUMN, // supports - a bit buggy
        //   // Charts.ChartType.COMBO, // should support but tests fails
        //   // Charts.ChartType.GAUGE, // does not have the colors option
        //   // Charts.ChartType.GEO, // does not have the colors option
        //   Charts.ChartType.HISTOGRAM, // supports
        //   Charts.ChartType.RADAR, // supports
        //   Charts.ChartType.LINE, // supports
        //   Charts.ChartType.ORG, // supports
        //   Charts.ChartType.PIE, // supports
        //   Charts.ChartType.SCATTER, // supports
        //   // Charts.ChartType.SPARKLINE,
        //   Charts.ChartType.STEPPED_AREA, // supports
        //   // Charts.ChartType.TABLE, // does not have the colors option
        //   // Charts.ChartType.TREEMAP, // does not have the colors option
        //   // Charts.ChartType.WATERFALL // should support but tests fails
        //   ]);
        // const pallete = palleteMap.get(chartID);
        // // const colors = JSON.parse("[" + pallete + "]");
        // eval("var colors = " + pallete + ";");

        // if(SUPPORTED_CHART_TYPES.has(chart.modify().getChartType())) {
        //   chart = chart.modify().setOption('colors', colors).build();

        //   myLogger.log("chart.modify().setOption('colors', [ " + colors.toString() +
        //     " ]), called for a chart: " + getChartInfo(chart));

        //   myLogger.log("chart.getOptions().get('colors'): [" + chart.getOptions().get("colors") +
        //     "], chart: " + getChartInfo(chart));
        //   sheet.updateChart(chart);
        //   myLogger.log("Chart " + chart.getChartId() + " updated.");
        //
        // }
        // else {
        //   myLogger.log("Error - ChartType is not supported (it probably does not have the 'colors' option). Chart: "
        //      + getChartInfo(chart));
        // }
      }
    }
  }

  myLogger.log("--- colorPieChartsWithPallete() ended ---");
  myLogger.flush();
}

What steps will reproduce the problem?

1. Uncomment any commented part with " of course... 🤦" comment
2. Run the script in the provided testing spreadsheet

What is the expected output? What do you see instead? If you see error messages, please provide them.

The expected output would be API not crashing randomly and API without race conditions so that the same setter does not need to be executed 10 times to get the colors set once...

Also the error messages are completely generic and not helpful at all.

E.g. "Exception: Unexpected error while getting the method or property get on object Charts.ChartOptions."... well but what exactly is unexpected? No one knows...