Chore: Improve typings (#88282)

* remove some type assertions

* some more type assertion fixes

* nicer

* shortcircuit while loop when hitting something that isn't an HTMLElement

packages/grafana-data/src/dataframe/processDataFrame.ts

@@ -149,7 +149,7 @@ function convertGraphSeriesToDataFrame(graphSeries: GraphSeriesXY): DataFrame {
 }
 
 function convertJSONDocumentDataToDataFrame(timeSeries: TimeSeries): DataFrame {
-  const fields = [
+  const fields: Field[] = [
     {
       name: timeSeries.target,
       type: FieldType.other,
@@ -158,7 +158,7 @@ function convertJSONDocumentDataToDataFrame(timeSeries: TimeSeries): DataFrame {
         unit: timeSeries.unit,
         filterable: (timeSeries as any).filterable,
       },
-      values: [] as TimeSeriesValue[][],
+      values: [],
     },
   ];
 
@@ -315,11 +315,11 @@ export function toDataFrame(data: any): DataFrame {
   if ('fields' in data) {
     // DataFrameDTO does not have length
     if ('length' in data && data.fields[0]?.values?.get) {
-      return data as DataFrame;
+      return data;
     }
 
     // This will convert the array values into Vectors
-    return createDataFrame(data as DataFrameDTO);
+    return createDataFrame(data);
   }
 
   // Handle legacy docs/json type