Check for errors after getting a response for all components

Some components were failing without internet connecttion and thus,
crashing the whole bar.

components/battery_level.go

@@ -22,7 +22,10 @@ const (
 )
 
 func main() {
-	response, _ := exec.Command("acpi", "-b", " | ", "grep", "Battery ", battery).Output()
+	response, err := exec.Command("acpi", "-b", " | ", "grep", "Battery ", battery).Output()
+	if err != nil {
+		return
+	}
 
 	iconPattern, _ := regexp.Compile("Full|Charging|Discharging")
 	powerPattern, _ := regexp.Compile("[0-9]+%")

components/cmus.go

@@ -8,7 +8,10 @@ import (
 )
 
 func main() {
-	response, _ := exec.Command("cmus-remote", "-Q").Output()
+	response, err := exec.Command("cmus-remote", "-Q").Output()
+	if err != nil {
+		return
+	}
 
 	artistPattern, _ := regexp.Compile("tag artist .*")
 	titlePattern, _ := regexp.Compile("tag title .*")

components/dark_sky_weather.go

@@ -29,7 +29,11 @@ const (
 
 func main() {
 	api_uri := fmt.Sprintf("https://api.darksky.net/forecast/%s/%s?exclude=minutely,hourly,daily,alerts,flags&units=%s", api_key, lon_lat, units)
-	response, _ := http.Get(api_uri)
+	response, err := http.Get(api_uri)
+	if err != nil {
+		return
+	}
+
 	data, _ := ioutil.ReadAll(response.Body)
 
 	var forecast interface{}

components/keyboard_layout.go

@@ -8,7 +8,11 @@ import (
 )
 
 func main() {
-	response, _ := exec.Command("setxkbmap", "-query").Output()
+	response, err := exec.Command("setxkbmap", "-query").Output()
+	if err != nil {
+		return
+	}
+
 	layoutPattern, _ := regexp.Compile("layout:\\s+[a-z]+")
 	layout := strings.TrimSpace(strings.Split(layoutPattern.FindString(string(response)), ":")[1])
 

components/volume_level.go

@@ -19,7 +19,10 @@ const (
 )
 
 func main() {
-	response, _ := exec.Command("amixer", "sget", "Master").Output()
+	response, err := exec.Command("amixer", "sget", "Master").Output()
+	if err != nil {
+		return
+	}
 
 	levelPattern, _ := regexp.Compile("[0-9]+%")
 	statusPattern, _ := regexp.Compile("\\[(on|off)\\]")