Use isEmpty check for empty strings

Author: itingliu

Sources/FoundationEssentials/Locale/Locale+Language.swift

@@ -34,11 +34,11 @@ extension Locale {
                 if let languageCode = languageCode {
                     result += languageCode._normalizedIdentifier
                 }
-                if let script = script, script != "" {
+                if let script = script, !script.identifier.isEmpty {
                     result += "-"
                     result += script._normalizedIdentifier
                 }
-                if let region = region, region != "" {
+                if let region = region, !region.identifier.isEmpty {
                     result += "_"
                     result += region._normalizedIdentifier
                 }

Sources/FoundationInternationalization/Locale/Locale+Components_ICU.swift

@@ -525,7 +525,7 @@ extension Locale.Language {
     public var minimalIdentifier : String {
         let componentsIdentifier = components.identifier
 
-        if componentsIdentifier == "" {
+        guard !componentsIdentifier.isEmpty else {
             // Just return "". Nothing to reduce.
             return componentsIdentifier
         }
@@ -548,7 +548,7 @@ extension Locale.Language {
     /// Returns a BCP-47 identifier that always includes the script: "zh-Hant-TW", "en-Latn-US"
     public var maximalIdentifier : String {
         let id = components.identifier
-        if id == "" {
+        guard !id.isEmpty else {
             // Just return "" instead of trying to fill it up
             return id
         }