Validate precipitation probabilities and ice wording

internal/weatherdata/bundle.go

@@ -3,6 +3,7 @@ package weatherdata
 
 import (
 	"encoding/json"
+	"math"
 	"time"
 )
 
@@ -137,6 +138,12 @@ func (p ForecastPeriod) HasUsableTimeBounds() bool {
 	return !p.StartTime.IsZero() && !p.EndTime.IsZero() && p.EndTime.After(p.StartTime)
 }
 
+// HasValidPrecipitationProbability reports whether an optional probability is a finite percentage.
+func (p ForecastPeriod) HasValidPrecipitationProbability() bool {
+	value := p.ProbabilityOfPrecipitationPercent
+	return value == nil || !math.IsNaN(*value) && !math.IsInf(*value, 0) && *value >= 0 && *value <= 100
+}
+
 type AlertRun struct {
 	AsOf   *time.Time        `json:"asOf,omitempty"`
 	Alerts []json.RawMessage `json:"alerts,omitempty"`