loki: handle parsing infinity in loki response (#45097)

public/app/plugins/datasource/loki/result_transformer.test.ts

@@ -295,6 +295,9 @@ describe('enhanceDataFrame', () => {
       [1, '1'],
       [2, '0'],
       [4, '1'],
+      [7, 'NaN'],
+      [8, '+Inf'],
+      [9, '-Inf'],
     ];
 
     it('returns data as is if step, start, and end align', () => {
@@ -303,6 +306,9 @@ describe('enhanceDataFrame', () => {
         [1, 1000],
         [0, 2000],
         [1, 4000],
+        [null, 7000],
+        [Infinity, 8000],
+        [-Infinity, 9000],
       ]);
     });
   });

public/app/plugins/datasource/loki/result_transformer.ts

@@ -192,11 +192,22 @@ function lokiMatrixToTimeSeries(matrixResult: LokiMatrixResult, options: Transfo
   };
 }
 
+function parsePrometheusFormatSampleValue(value: string): number {
+  switch (value) {
+    case '+Inf':
+      return Number.POSITIVE_INFINITY;
+    case '-Inf':
+      return Number.NEGATIVE_INFINITY;
+    default:
+      return parseFloat(value);
+  }
+}
+
 export function lokiPointsToTimeseriesPoints(data: Array<[number, string]>): TimeSeriesValue[][] {
   const datapoints: TimeSeriesValue[][] = [];
 
   for (const [time, value] of data) {
-    let datapointValue: TimeSeriesValue = parseFloat(value);
+    let datapointValue: TimeSeriesValue = parsePrometheusFormatSampleValue(value);
 
     if (isNaN(datapointValue)) {
       datapointValue = null;