Fix typos in comments (#3415)

metric/parse.go

@@ -647,7 +647,7 @@ func skipWhitespace(buf []byte, i int) int {
 }
 
 // makeError is a helper function for making a metric parsing error.
-//   reason is the reason that the error occured.
+//   reason is the reason why the error occurred.
 //   buf should be the current buffer we are parsing.
 //   i is the current index, to give some context on where in the buffer we are.
 func makeError(reason string, buf []byte, i int) error {

metric/reader_test.go

@@ -181,7 +181,7 @@ func TestMetricReader_SplitWithExactLengthSplit(t *testing.T) {
 	}
 }
 
-// Regresssion test for when a metric requires to be split and one of the
+// Regression test for when a metric requires to be split and one of the
 // split metrics is larger than the buffer.
 //
 // Previously the metric index would be set incorrectly causing a panic.
@@ -218,7 +218,7 @@ func TestMetricReader_SplitOverflowOversized(t *testing.T) {
 	}
 }
 
-// Regresssion test for when a split metric exactly fits in the buffer.
+// Regression test for when a split metric exactly fits in the buffer.
 //
 // Previously the metric would be overflow split when not required.
 func TestMetricReader_SplitOverflowUneeded(t *testing.T) {