fix a couple issues and add some extra logging/error details

src/api.ts

@@ -207,10 +207,14 @@ export function fetchAll(requests: MatomoRequestParams[], options: ApiFetchOptio
           return; // retry
         }
 
+        const content = r.getContentText('UTF-8');
+
         responseContents[responseIndex] = {
           result: 'error',
-          message: `Matomo server failed with code ${code}. Truncated response: ${r.getContentText('UTF-8').substring(0, 100)}`,
+          message: `Matomo server failed with code ${code}. Truncated response: ${content.substring(0, 100)}`,
         };
+
+        debugLog(`Whole response: ${content}`);
       } else {
         // save the response even if it's an error so we can get the server-side error message if needed
         responseContents[responseIndex] = r.getContentText('UTF-8') || '{}';

src/data.ts

@@ -201,7 +201,7 @@ export function getSchema(request: GoogleAppsScript.Data_Studio.Request<Connecto
 
     const result = { schema: fields.build() };
 
-    debugLog('getSchema(): result is', result);
+    debugLog('getSchema(): result is', JSON.stringify(result));
 
     return result;
   });

src/schema/data-types.ts

@@ -100,7 +100,11 @@ export function convertMatomoTypeToLooker(value: any, matomoType: string) {
   return `${value}`;
 }
 
-export function mapMatomoAggregationTypeToLooker(matomoAggregation: string): AggregationType|undefined {
+export function mapMatomoAggregationTypeToLooker(matomoAggregation?: string): AggregationType|undefined {
+  if (!matomoAggregation) {
+    return undefined;
+  }
+
   switch (matomoAggregation.toLowerCase()) {
     case 'avg':
       return cc.AggregationType.AVG;

src/schema/formula.ts

@@ -220,16 +220,27 @@ function toLookerString(ast: MathNode): string {
   }
 }
 
-export function mapMatomoFormulaToLooker(formula: string): {
-  lookerFormula: string,
+export function mapMatomoFormulaToLooker(formula?: string): {
+  lookerFormula?: string,
   temporaryMetrics: string[],
 } {
-  const ast = math.parse(formula);
+  if (!formula) {
+    return {
+      temporaryMetrics: [],
+    };
+  }
+
+  let ast;
+  try {
+    ast = math.parse(formula);
+  } catch (e) {
+    throw new Error(`Failed to parse formula '${formula}': ${e.stack || e.message || e}`);
+  }
 
   const temporaryMetrics = [];
   ast.traverse((node) => {
     if (node.type === 'SymbolNode' && (node as SymbolNode).name.startsWith('$')) {
-      temporaryMetrics.push((node as SymbolNode).name);
+      temporaryMetrics.push((node as SymbolNode).name.substring(1));
     }
   });
 

src/schema/report-metadata.ts

@@ -277,8 +277,8 @@ export function getFieldsFromReportMetadata(
   });
 
   allTemporaryMetrics.forEach((metricId) => {
-    const aggregationType = reportMetadata.temporaryMetricAggregationTypes[metricId];
-    const matomoType = reportMetadata.temporaryMetricSemanticTypes[metricId];
+    const aggregationType = reportMetadata.temporaryMetricAggregationTypes?.[metricId];
+    const matomoType = reportMetadata.temporaryMetricSemanticTypes?.[metricId];
 
     if (!matomoType) {
       return;