SMAP time series analysis error in code

Input are: NASA/SMAP/SPL4SMGP/007 NASA/GPM_L3/IMERG_MONTHLY_V06

When I try to compute the time series I get the following error:

ImageCollection (Error) reduce.mean: Error in map(ID=20200601_0130): Image.select: Pattern 'ssma' did not match any bands.

Anyone knows what is happening here? I added the code below.

var basin_boundary = geometry2

// Add basin boundary in the map.
Map.addLayer(basin_boundary, {}, 'Area of interest');
Map.centerObject(basin_boundary, 7);

// Define study period.
var startYear = 2020;
var endYear = 2024;
var startMonth = 1;
var endMonth = 12;

var startDate = ee.Date.fromYMD(startYear, startMonth, 1);
var endDate = ee.Date.fromYMD(endYear, endMonth, 31);
var years = ee.List.sequence(startYear, endYear);
var months = ee.List.sequence(1, 12);

// Define a function to convert GPM IMERG from mm/hr to mm/day.
var gpmScale = function(image) {
  return image.multiply(24)
              .copyProperties(image, ['system:time_start']);
};

// Define a function to compute the anomaly for a given month.
var computeAnomalyPrecipitation = function(image) {
  // Get the month of the image.
  var year = image.date().get('year');
  var month = image.date().get('month');
  // Get the corresponding reference image for the month.
  var referenceImage = meanMonthlyPrecipitation.filter(
      ee.Filter.eq('month', month)).first();
  // Check if the images have bands
  var hasBands = image.bandNames().size().gt(0);
  // Compute the anomaly by subtracting reference image from input image.
  var anomalyImage = ee.Algorithms.If(
    hasBands,
    image.subtract(referenceImage),
    image);

  return ee.Image(anomalyImage).set(
    'system:time_start', ee.Date.fromYMD(year, month, 1).millis());
};

// Anomalies surface and subsurface soil moisture (mm).
var ssSusMa =  nasa_usda_smap
  .filterDate(startDate, endDate)
  .sort('system:time_start', true)  // sort a collection in ascending order
  .select(['ssma', 'susma']);  // surface and subsurface soil moisture bands

// Compute monthly anomalies surface and subsurface soil moisture.
var monthlySsSusMa =  ee.ImageCollection.fromImages(
  years.map(function(y) {
    return months.map(function(m) {
      var filtered = ssSusMa.filter(ee.Filter.calendarRange(y, y, 'year'))
                         .filter(ee.Filter.calendarRange(m, m, 'month'))
                         .mean();
      return filtered.set(
        'system:time_start', ee.Date.fromYMD(y, m, 1).millis());
    });
  }).flatten()
);

// Precipitation from monthly GPM IMERG Final product (mm/day).
var rawMonthlyPrecipitation =
  gpm_imerg
  .select('precipitation')
  .filterDate(startDate, endDate)
  .sort('system:time_start', true)
  .map(gpmScale); // convert rainfall unit from mm/hr to mm/d

// Make sure monthly precipitation has same duration as soil moisture.
var monthlyPrecipitation =  ee.ImageCollection.fromImages(
  years.map(function(y) {
    return months.map(function(m) {
      var filtered = rawMonthlyPrecipitation
                          .filter(ee.Filter.calendarRange(y, y, 'year'))
                          .filter(ee.Filter.calendarRange(m, m, 'month'))
                          .mean();
      return filtered.set({
        'month': m,
        'system:time_start': ee.Date.fromYMD(y, m, 1).millis()
      });
    });
  }).flatten()
);

// Compute climatological monthly precipitation.
var meanMonthlyPrecipitation = ee.ImageCollection.fromImages(
  ee.List.sequence(1, 12).map(function(m) {
    var filtered = monthlyPrecipitation.filter(ee.Filter.eq('month', m)).mean();
    return filtered.set('month', m);
  })
);

// Map the function over the monthly precipitation collection to compute
// the anomaly precipitation for each month.
var monthlyPrecipitationAnomalies = monthlyPrecipitation.map(
    computeAnomalyPrecipitation);
    
// Combine two image collections into one collection.
var smpreDatasets  = monthlySsSusMa.combine(monthlyPrecipitationAnomalies);
print('soil moisture and precipitation', smpreDatasets);

var chart =
  ui.Chart.image.series({
      imageCollection: smpreDatasets,
      region: basin_boundary,
      scale: 10000,
      xProperty: 'system:time_start'
    })
    .setSeriesNames(['surface SM', 'subsurface SM', 'precipitation'])
    .setOptions({
      title: 'Anomalies time series: surface soil moisture, sub-surface soil ' +
       'moisture, and precipitation',
      series: {
        0: {
            targetAxisIndex: 0, type: 'line', lineWidth: 3,
            pointSize: 1, color: '#ffc61a'
        },
        1: {
            targetAxisIndex: 0, type: 'line', lineWidth: 3, pointSize: 1,
            lineDashStyle: [2, 2], color: '#330000'
        },
        2: {
            targetAxisIndex: 1, type: 'line', lineWidth: 3, pointSize: 1,
            lineDashStyle: [4, 4], color: '#1a1aff'
        },
      },
      hAxis: {
        title: 'Date',
        titleTextStyle: {italic: false, bold: true}
      },
      vAxes: {
        0: {
            title: 'soil moisture (mm)',
            baseline: 0, titleTextStyle: {bold: true, color: '#ffc61a'},
            viewWindow: {min: -4, max: 4}
        },
        1: {
            title: 'precipitation (mm)',
            baseline: 0, titleTextStyle: {bold: true, color: '#1a1aff'},
            viewWindow: {min: -2.5, max: 2.5}
        }
      },
      curveType: 'function'
    });

print(chart);

// Setup colors for soil moisture anomalies.
var palette = ['8c510a', 'bf812d', 'dfc27d', 'f6e8c3', 'ffffff',
               'ffffff', 'c7eae5', '80cdc1', '35978f', '01665e'];
var smVis = {
  min: -4,
  max: 4,
  opacity: 0.9,
  palette: palette,
};
// Setup colors for precipitation anomalies.
var preVis = {
  min: -3,
  max: 3,
  opacity: 0.9,
  palette: palette,
};
// Filter soil moisture to May 2021, subset first image, and clip to AOI.
var thisSsSusMa = monthlySsSusMa.filterDate(
  '2021-05-01', '2021-05-31').first().clip(basin_boundary);
// Filter precipitation to May 2021, subset first image, and clip to AOI.
var thisPre = monthlyPrecipitationAnomalies.filterDate(
  '2021-05-01', '2021-05-31').first().clip(basin_boundary);

// Display the images on the map.
Map.addLayer(thisSsSusMa.select('ssma'), smVis, 'Surface Soil Moisture');
Map.addLayer(thisSsSusMa.select('susma'), smVis, 'Subsurface Soil Moisture');
Map.addLayer(thisPre, preVis, 'Precipitation');